Archive of Our Own

The idea didn't originate from Nicholas’ brain, though it easily could have. It was exactly the kind of ridiculous thing he would think up at three in the morning when he couldn't sleep.

"Bet you could use this kind of conditioning to make someone pop a boner every time they heard bells or something."

The words had come from Yuma’s careless mouth less than two weeks ago during one of their study breaks. The two of them had been crammed into the library, half-awake and running on caffeine while revising for their upcoming exam.

At the time, Nicholas had laughed it off and told Yuma he was an idiot. Now, two weeks later, Nicholas unfortunately has begun to wonder if Yuma had been onto something because he couldn't get the thought out of his mind.

Classical conditioning is an unconscious or automatic learning process that involves creating an association between an unconditioned stimulus and a neutral stimulus to elicit a conditioned response. Back in the 1890s, Pavlov designed a controlled experiment to see if he could teach a dog to start salivating at the sound of a bell. 

Experiments play a very fundamental role in the field of psychology, a lot of discoveries were made through experiments, most often unethical ones. They determine cause-and-effect by manipulating an independent variable, the cause, and measuring the dependent variable, the effect.

As a future research psychologist, Nicholas will be conducting a lot of experiments. It's never too early to start practicing and what better way to do it than to use his precious unassuming boyfriend, Euijoo, as a guinea pig. 

He already looks like a wet dog most of the time so it's truly fitting.

Said boyfriend is currently sitting at the small kitchen table in the apartment Nicholas shares with him, mumbling to himself while he's trying to calculate something. Nicholas doesn't really know what Euijoo does most of the time when he's working on assignments. 

He's a physics major so probably finding the value of x or something.

Nicholas picks up his notebook and pen, then opens a blank page, a good researcher always takes notes.

Experiment Log: Nicholas’ dog (very creative)

Researcher: Wang Yixiang

Subject: Male, age 22. Current relationship to researcher: boyfriend.

Objective:
To determine whether a neutral auditory stimulus (small bell chime) can become associated with physiological sexual arousal through repeated pairings with positive romantic and intimate experiences.

Hypothesis:
If a specific bell sound is consistently presented immediately before moments of physical affection and intimacy, the subject will eventually exhibit signs of anticipatory arousal upon hearing the bell alone.

Nicholas sets down the pen and looks back up at Euijoo who seems to be on the verge of tears. 

There are several components Nicholas has to account for if he wants this experiment to work.

First comes the Unconditioned Stimulus (US). In classical conditioning, the unconditioned stimulus is something that naturally and automatically produces a response without any prior learning. A cold breeze causing someone to shiver is a simple example—the breeze is the stimulus, and the shiver happens involuntarily. In Nicholas' experiment, the unconditioned stimulus is any form of physical intimacy that naturally leads to arousal: affection, kissing, physical touch, or sexual activity.

Conveniently for him, this part requires very little effort. Euijoo gets alarmingly easy turned on. Sometimes all it takes is a few minutes of kissing.

Next is the Unconditioned Response (UCR), the automatic reaction produced by the unconditioned stimulus. Since the intimacy itself naturally causes arousal, the arousal is the unconditioned response. No learning is required; it happens on its own.

Then there's the Neutral Stimulus (NS). A neutral stimulus is something that initially produces no meaningful response related to the behavior being studied. In this case, that's the bell. Before conditioning begins, the sound means nothing to Euijoo. It's simply a noise. He might notice it, recognize it, or even comment on it, but it has no connection to arousal whatsoever.

After enough pairings between the neutral stimulus and the unconditioned stimulus, the bell undergoes a promotion of sorts. It becomes the Conditioned Stimulus (CS). In other words, it transforms from a meaningless sound into a signal that predicts something else. The bell itself hasn't changed, but Euijoo's brain will have learned learned to associate it with intimacy through repeated exposure.

Finally comes the Conditioned Response (CR). This is the learned reaction that develops once the association has been established. Ideally, the conditioned response mirrors the original unconditioned response. If everything works the way the textbooks say it should, hearing the bell alone will begin to trigger arousal even when intimacy doesn't immediately follow.

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The experiment officially begins the following day. Nicholas even skips his last class so he can take the bus into town and buy the bell he needs. Technically, he could've waited until after class but he knows that Euijoo will be waiting for him so that they can walk back home together and Nicholas doesn't have the mental capacity to come up with a lie as to why he skipped.

As he browses the shelves lined with bells of every shape and size, a strange excitement starts bubbling in his chest. He smiles to himself when he picks up a small silver bell from one of the displays. It's light enough to carry around in his pocket but loud enough to be heard clearly.

Nicholas makes it back to campus with only a few minutes to spare and when he walks out the building he sees Euijoo already waiting there for him.

He's impossible to miss. Partly because Euijoo is tall enough to stand out in a crowd but the bright red Spider-Man backpack hanging from one shoulder also plays a role in that. It sticks out amongst the sea of plain backpacks and messenger bags carried by every other university student. 

Euijoo truly is the walking stereotype sometimes with his stupidly cute glasses, his endless collection of shirts with science puns on them hidden beneath his hoodies and his freakishly adorable obsession with super heroes. 

Euijoo is such a nerd and Nicholas wants nothing more than to have him shove his tongue down his throat.

Nicholas watches him from across the courtyard for a moment. Euijoo is looking down at his phone, occasionally pushing his glasses back up his nose while he waits. He doesn't appear annoyed or impatient. He's simply standing there because he said he would be. Waiting for Nicholas.

He feels ridiculously happy all of a sudden. Happy enough that he almost starts skipping over to where Euijoo is standing and throw himself against Euijoo the moment he gets close enough.

However, Yuma is lurking around here somewhere and he possesses an almost supernatural ability to appear whenever Nicholas is doing something embarrassing. If he catches Nicholas skipping across the courtyard like some lovesick idiot then he’ll be teased to death.

"Remember that time you saw Euijoo and nearly frolicked across campus?"

Absolutely not, Nicholas refuses to give him that kind of ammunition therefore he forces himself to maintain a normal pace, shoves his hands into his pockets and adopts what he hopes is a casual expression.

Euijoo notices Nicholas approaching and immediately pushes himself away from the wall. He slips his phone into his back pocket before looking up fully.

“Sup, nerd,” Nicholas says as he slows to a stop right in front of him.

Euijoo doesn’t answer, his expression softens and the corners of his mouth lift up as he breaks into a small, fond smile. He reaches up and adjusts his cap, turning it backwards so the brim won’t get in his way. Then he steps closer, bridging the small gap between them until there’s barely any space left. He leans in and because of their minor difference in height, he has to dip his head slightly before he presses a sweet lingering kiss to Nicholas' lips.

The gesture is so simple yet so infuriatingly attractive, it has Nicholas’ entire body heating up. Every coherent thought promptly abandons him. Truly ridiculous how easily Euijoo affects him. 

He is pissed off. He wants that stupid nerd so bad.

It seems that the feeling is mutual because instead of pulling away, Euijoo leans in even further. The kiss deepens naturally with neither of them willing to be the first to create distance and Nicholas feels his pulse jump in response.

Seconds later, Euijoo's hands find their way to Nicholas' lower back, the touch is familiar yet it affects him every single time, and Euijoo draws him closer until there's barely any space left between them. The gesture is possessive in the gentlest way possible—a quiet declaration that he wants Nicholas closer.

The moment they step through the apartment door, Euijoo makes a beeline straight for their bedroom because he's got this thing where he needs to take everything off the second he gets home. The cap, the watch, the bracelets, the rings, the hoodie—anything that can be removed is removed within the first five minutes of entering.

Euijoo disappears down the hallway already tugging at the sleeves of his hoodie as he goes and Nicholas follows him. 

The bedroom is warm from the afternoon sun, Euijoo steps directly into it and begins his usual ritual. The two rings he was wearing today clatter on the surface of the dresser, then he takes off his bracelets and lastly his watch. The only thing Euijoo leaves on is the silver necklace Nicholas got him for his birthday. 

Euijoo never takes it off. It stays on all the time–when he sleeps, when he showers, when he's lounging around the apartment, when they have sex and it dangles right in Nicholas’ face–the necklace has become a part of Euijoo and Nicholas tries not to think too much about how much he likes that.

While he's at it Nicholas might as well also change into more comfortable clothes. It's Friday afternoon and as far as Nicholas is concerned, the outside world no longer exists until Monday morning.

Once Nicholas is changed he drops onto the edge of the bed with a relieved sigh and watches Euijoo get undressed while he's telling him about his thermodynamics lab.

"...and then my lab partner somehow got a completely different value even though we were literally using the same numbers."

Euijoo continues talking and Nicholas listens attentively until he sees Euijoo reach over his shoulder and pull his shirt over his head.

"...because enthalpy depends on the total energy of the system—"

Nicholas' ability to pay attention begins to deteriorate because it's really hard to concentrate when he's got Euijoo’s naked upper body on full display. He even blushes when he notices the scratches he left on Euijoo’s back last night, they're still slightly red. He makes a mental note to put something on them later.

Euijoo seems to be oblivious about the hungry looks he's getting from his boyfriend because he's still enthusiastically talking about his findings. It's endearing whenever Euijoo rambles because he is a very quiet person majority of the time. 

Put Euijoo in a room full of strangers and he'll happily spend the entire evening observing everyone else. Rarely speaks unless spoken to but get him comfortable and talking about something he genuinely loves and it's like watching a completely different person emerge. The words start flowing faster than he can organize them. One topic turns into another and another and another. Entire tangents appear out of nowhere before looping back to the original subject ten minutes later. 

His eyes brighten, his hands start moving when he talks and becomes animated in a way that surprises people who only know the quieter version of him.

Nicholas adores that side of him even if he doesn’t understands any of the science. Really,  Euijoo could be explaining advanced thermodynamics or the secret ritual required to summon a demon into their kitchen sink, and Nicholas' level of comprehension would be roughly identical but he loves listening anyway.

Eventually, Euijoo disappears into the bathroom, though his voice continues carrying through the open door while he's talking about band practice now.

Nicholas twists around on the bed and glances at the digital clock sitting on Euijoo's nightstand. "What time does practice start?"

A loud metallic clank follows and Nicholas winces. Apparently Euijoo has knocked something over. Nicholas hears him mutter a curse under his breath before answering, "I have to be there at seven-thirty."

Nicholas checks the clock again as he mentally calculates the schedule. It's four-fifteen right now and Euijoo will probably start getting ready around six-thirty so that leaves nearly three hours to execute the first step of the experiment which is baseline observation. 

Before introducing any associations and attempting any conditioning, you need to know how the subject responds to each stimulus independently. Otherwise, how are you supposed to measure change.

Nicholas could've started with the reaction to the bell but that's boring, especially when he's all hot and bothered so he's going to start by seeing how Euijoo reacts to the unconditioned stimulus—the physical intimacy. 

Not that there's anything new to discover because Nicholas already knows exactly how Euijoo tends to react whenever he makes a move on him, suggesting that they'd fool around a little—like an overly excited golden retriever being given a shiny bone to gnaw on.

It's not even remotely difficult to interpret and he's essentially preparing to confirm something he already knows but a good scientist verifies their assumptions and doesn't rely on prior observations.

Science, after all, demands thoroughness.

Nicholas hurries off the bed and walks over to the bathroom door. He reaches the door at the exact moment Euijoo steps out, and the two of them nearly collide.

Euijoo takes a startled step back.

Nicholas smiles slyly, hooks his fingers into the waistband of his sweatpants and gently tugs Euijoo closer. Nicholas then slides his arms around his neck, fingers threading into the hair at the nape of it. The strands are soft beneath his touch, slightly damp from where Euijoo had splashed water on his face in the bathroom.

Nicholas feels the full-body shudder from Euijoo and his grins widens. Hook. Line. Sinker. For someone who usually keeps his emotions tucked away behind a calm exterior, Euijoo is hopelessly easy to read when it comes to Nicholas.

Euijoo's eyes soften. Whatever he had been saying about band practice dies on his lips and now looks at Nicholas like he's forgotten his own name. His hands find Nicholas' waist, settling there as naturally as breathing.

When their lips slot together Euijoo makes an embarrassingly needy noise and Nicholas feels him relax beneath his hands. He likes how easily they melt against each other like two puzzle pieces finding their place.

Their tongues slide together and Nicholas hums in contentment. He sucks on Euijoo’s a little, enough to make Euijoo go slightly weak-kneed. When they eventually pull back to catch their breaths, a string of saliva is pulled taut between before it breaks. 

They remain close enough that their foreheads brush together, their breaths mingling in the small space between them. Euijoo's eyes are slightly unfocused as he looks at Nicholas, his chest rising and falling noticeably faster than before. His usually neat hair is a mess now from Nicholas' fingers.

Euijoo immediately pulls Nicholas back into another kiss, they're going at it with a lot more force and hunger. Nicholas finds himself smiling against Euijoo's lips as he guides them backward through the room. Neither of them is paying much attention to where they're going until the edge of the bed bumps against the back of Euijoo's legs.

Nicholas gives him a gentle push and Euijoo falls onto the bed with a surprised laugh before he comes to stand in between Euijoo’s legs, looking down at him. Euijoo is looking back at him, his pupils are blown wide, his chest is rising and falling and he looks like he's in a trance. 

Nicholas climbs on top of him.

"Oh my God," Euijoo mutters breathlessly.

Nicholas grins then puts his entire weight onto Euijoo's lap. The mattress shifts beneath them as his knees land on either side of Euijoo's hips, effectively trapping him against the bed. 

Nicholas barely gives him a second to recover before leaning down and kissing him again. Euijoo makes a soft, helpless sound and tilts his head up to meet him halfway. Nicholas can't help smiling into the kiss.

He's so easy, then again, it's not like Nicholas is feigning any better. It's very clear that they're both horny.

He has Euijoo caged in and slips his tongue into his mouth to which Euijoo lets out a loud moan. Euijoo also doesn't waste any time getting his hands all over Nicholas, it’s a shame really that he only has two. First they're tangled in Nicholas's hair, fingers threading through the strands and lightly scratching against his scalp. Then they slide lower, tracing the length of his back. They never stay in one place for long, it's as if Euijoo can't decide where he wants to touch him most.

His hands drift down further all the way to Nicholas’ thighs then back up until they're hovering over the hem of Nicholas’ shirt. 

Nicholas is waiting for Euijoo to put his hand on his bare skin but his idiot boyfriend is hesitating. He clicks his tongue in annoyance and rocks his hips forward, spurring Euijoo on.

Nicholas is rewarded with a beautiful moan falling from Euijoo’s lips. Euijoo no longer hesitates and puts his hands exactly where Nicholas wants them, he slips them into Nicholas’ shirt and his warm palms rest on his waist, bringing Nicholas closer and they both marvel at the feeling of it all.

Euijoo is now fully hard. Nicholas can feel him through the thin layers of their basketball shorts and continues grinding against him. He goes all pliant in Nicholas’ palms, opening up and allowing Nicholas to drink up the whines he's releasing. 

Nicholas’ head spins and his stomach is hot, coiling with pleasure but he isn't letting up, neither is Euijoo with his firm grip guiding Nicholas’ hips against him. 

They're panting and moaning into each other's mouths like a bunch of hormone-drunk teenagers. Euijoo’s hips suddenly kick up, chasing the pressure and Nicholas smiles proudly because he knows what that means. Seconds later Euijoo lets out a chocked little sob as he cums.

Nicholas coaxes him through it with soft murmurs, petting his hair until Euijoo’s is back on earth spiritually.

“That was fast.” Nicholas says teasingly, nipping at Euijoo’s neck while he continues to bring himself over the edge.

Euijoo gives a half-hearted protest that doesn’t hold much weight, still catching up to himself. “I was just… really—” He pauses, struggling, then gives up entirely with a small exhale. “Pent up.”

Nicholas can't see his face but the heat radiating from his neck tells him that he's blushing furiously.

So adorable.

Baseline Observation: Reaction to Unconditioned Stimulus

Day 1

Objective: Establish baseline response to the unconditioned stimulus prior to the introduction of the neutral stimulus.

Observations:
Subject demonstrated a strong and enthusiastic response to the unconditioned stimulus, consistent with initial expectations. Signs of physiological arousal were observed within approximately 10 seconds of physical contact.

Subject appeared highly receptive to the stimulus throughout the observation period and required minimal prompting to engage with the interaction.

Results:

• Response latency: ~10 seconds

• Response intensity: High

• Consistency: Reliable

Additional Notes:
Subject self-reported being "pent up," which may have contributed to the unusually rapid onset and intensity of the observed response. Potential confounding variable should be noted for future observations.

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Baseline Observation: Reaction to Neutral Stimulus

Day 2

Objective: Assess subject response to repeated presentations of the neutral stimulus in the absence of conditioning pairings.

Procedure:
The bell stimulus was presented on three separate occasions throughout the day, without any accompanying unconditioned stimulus.

Observations:
Subject demonstrated no measurable physiological or behavioral response to the stimulus across all trials. No indication of recognition, anticipation, or association formation was observed.

Subject did, however, verbally inquire about the presence and purpose of the bell, suggesting awareness of the stimulus but not its significance.

Results:

• Response to stimulus: None detected

• Recognition: Present (verbal inquiry)

• Association formation: Not established

Additional Notes:

No confounding physiological responses observed at this stage.
Researcher maintained experimental integrity by redirecting subject inquiry and avoiding disclosure of experimental intent.

Current Recommendation:
Secure experimental materials when not in use, as subject is a nosy motherfucker.

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Nicholas decides to leave Euijoo alone on Sunday.

Partly because Euijoo spends nearly half the day on FaceTime with his parents. It starts sometime after breakfast and somehow stretches well into the afternoon. Nicholas has long since stopped questioning how people can spend that many hours talking to their parents every single week without running out of things to say.

The second reason is because Nicholas is profoundly lazy.

It's Sunday, which means he has absolutely no desire to do anything remotely productive. As far as he's concerned, the entire purpose of Sundays is to avoid responsibility at all costs. He wants to sleep until noon, drag himself out of bed solely because he's hungry, spend an unreasonable amount of time deciding what to eat, bother Euijoo for attention whenever the FaceTime call eventually ends, and then return to bed as soon as possible — Ideally with Euijoo.

The future of science can survive one day without Nicholas' contributions. So the bell remains untouched inside his desk drawer and the notebook stays there too, abandoned beside it.

Euijoo doesn't have classes on Monday, which means Nicholas already knows exactly where he'll be when he gets back from his last lecture of the day.

The walk home is spent thinking about the experiment. The conditioning phase has officially begun, which means Nicholas should probably have some sort of strategy. The process is straightforward enough. Present the neutral stimulus, follow it with the unconditioned stimulus and repeat often enough for an association to form. That's the entire foundation of classical conditioning.

He comes up with a few ways on how to approach this first step but all the ideas he accumulated go out the window the moment he steps into the living room and finds Euijoo on the couch, taking up the entire thing wearing one of his painfully nerdy science t-shirts and a pair of comfortable  basketball shorts.

His laptop is open on the coffee table in front of him, several sheets of paper are scattered around it, a calculator sits abandoned near his knee and he throws his head back against the couch cushion with a very frustrated groan, muttering something under his breath. 

There's just something so undeniably attractive about seeing Euijoo get frustrated. Thank the heavens above the man chose a major specifically designed to test the limits of human sanity.

Nicholas crosses the living room and approaches Euijoo from behind, sliding his hands over his neck down to his chest and slipping his hand into the front of his shirt. Euijoo doesn't flinch in surprise when Nicholas touches him, meaning that he knew Nicholas was here but he does inhale sharply.

"Welcome back," Euijoo says, tipping his head backward until he's looking up at Nicholas upside down and his glasses are slightly crooked.

"Hey, baby." Nicholas leans down and presses a quick kiss to Euijoo's lips. "What's got you so worked up?"

Euijoo lets out a heavy sigh that sounds like it's carrying the weight of several generations.

"This."

He gestures toward the laptop, Nicholas looks at the screen. It is covered in equations that contain so many letters, symbols, brackets, and mathematical horrors. They make zero sense in his mind and apparently also in Euijoo’s. 

"I've been stuck on this for almost an hour," Euijoo says miserably. "I know I made a mistake somewhere, but I can't figure out where."

Nicholas narrows his eyes at the screen and leans closer. After several seconds of fake contemplation, he points confidently toward the screen and says, "You forgot to carry the one."

Euijoo launches himself forward. "What?" His eyes dart across the equation. "Where?"

Nicholas chuckles and pinches Euijoo’s cheek affectionately. “I’m just messing with you, baby. I have no idea what any of this means.”

Euijoo deflates like a balloon slumping back again against the couch and Nicholas gives him a loving pat on the cheek before disappearing into the bedroom. 

Nicholas wastes no time changing into something more comfortable because he's not going to give his boyfriend head in jeans that he’s been wearing since eight in the morning, not when he has the opportunity to wear something else. He then slides the drawer open and retrieves the small bell, turning it once between his fingers before slipping it into his pocket. 

This time, instead of approaching from behind, he walks straight up to the couch and stops between Euijoo's legs. 

Normally, Nicholas considers manspreading a crime against humanity. He's spent years judging random men on public transportation for occupying enough space for three people. It's rude. It's annoying. It's completely unnecessary. As always Euijoo is his exception, he seems to get away with things that would irritate Nicholas if literally anyone else did them.

Euijoo looks Nicholas up and down and smiles cutely. Poor guy has absolutely no idea what is coming his way. 

"Are you tired? Do you want to take a nap?"

Nicholas can feel his heart turning into liquid and dripping through the gaps between his ribs. It's so ridiculous really because there is nothing particularly romantic about asking someone if they're tired. But it's the thought behind it that's so important. 

Euijoo knows Nicholas always crashes after his classes, knows that no matter how much sleep he got the night before, he'll inevitably end up taking a nap at some point during the afternoon. More importantly, Euijoo always makes room for it.

Euijoo rarely naps during the day. Even when he's exhausted, he'd rather occupy himself with something else than crawl into bed for an hour, yet whenever Nicholas wants to sleep, Euijoo will pause whatever assignment he's working on, close whatever tab he has open, and follow Nicholas to the bedroom without hesitation.

Sometimes he reads while Nicholas sleeps,  scrolls through his phone or simply lies there beside him with an arm wrapped around his waist, keeping him company until he wakes up.

Nicholas loves this idiot.

“No. I’ve got something else in mind.” 

“Oh. Okay. What do you wa—”

Euijoo's sentence dies in his throat when Nicholas drops to his knees between his legs, hands settling on his thighs for balance.

“Nichol. What are you doing?” Euijoo asks in a careful tone but his breathlessness doesn't go unnoticed.

“What's it look like?” Nicholas says blinking up at Euijoo and batting his eye lashes.

He's doing it on purpose to get Euijoo going, he knows exactly how he looks from Euijoo’s point of view. There's an old iphone 5 in a drawer in Euijoo’s bedside table with plenty of pictures and videos that show just how good he looks on his knees with Euijoo’s dick in his mouth. 

Euijoo lets out a shaky breath, Nicholas notices the way his hips shift with interest. “Okay, sure. Yeah. Whatever you want.”

Bingo.

Unable to hide his satisfaction, Nicholas reaches for the waistband of Euijoo’s shorts and hastily tugs them down, revealing Euijoo’s boxers of the day — red ones with spider-man’s face plastered all over them. 

Euijoo makes an embarrassed noise but Nicholas has to bite down on his lips to stop himself from moaning out loud. He doesn't know what it is but these stupid nerdy boxers have his dick twitching in his own shorts. 

Euijoo has done irreversible damage to him.

“Fuck, you're so hot, Juju.” 

Euijoo goes to cover himself up but Nicholas swats his hand away and leans over his lap so that his mouth is hovering above Euijoo’s bellybutton which is still hidden by the shirt. Nicholas lifts it up and pauses, he then looks up at Euijoo through his lashes and rings the bell, hidden away from Euijoo’s view, seconds before he licks a broad strip across his stomach. 

Euijoo’s stomach contracts, lets out a whiny moan and Nicholas feels his semi-hard-on against his arm. He continues leaving feather light kisses down Euijoo’s abdomen all the way down to his boxers. He then takes the waistband in between his teeth and pulls them down, all without breaking eye contact once.

“Oh my god, Nichol, what the hell.” — and Euijoo’s fully hard now. Nicholas grins exultantly, he just knows what he's doing or maybe Euijoo’s just too easy for him, either way Nicholas feels proud.

Euijoo’s cock springs free, hard and flushed. Nicholas wets his lips absentmindedly, gripping him by the base. He loves this. He glances up at Euijoo, who takes a shaky breath, before Nicholas pressed the head past his lips, tongue swirling around it and hand seated firmly at the base. First Nicholas works him through the initial sensitivity before slowly taking him deeper. 

“Fuck,” Euijoo swears loudly, his hands immediately going into Nicholas’ hair and Nicholas can't help but smile around the mouthful of cock. 

Since Nicholas doesn't have a gag reflex he gets to really have fun with this, rips out a few beautiful moans out of Euijoo’s throat when he hits the back of Nicholas’ tongue. 

The deeper he takes Euijoo the more he's getting his hair tugged on. Nicholas despises people touching his hair but in this particular instance he quite enjoys the pleasant tingle on his scalp. 

Nicholas hums around him, bobbing his head and letting his jaw fall slack as he gets into the perfect rhythm. Judging from the sounds Euijoo is letting out, he's probably doing a good job. Of course he is because if there's one thing Nicholas is good at, apart from getting on Euijoo’s last nerves, it's giving him a blowjob. 

He would consider himself a professional in some kind of way, he’s had years of practice and he does it with a lot of enthusiasm. Yuma pointed out that it's probably due to Nicholas’ strange need to keep putting things in his mouth. 

In psychology, oral fixation is viewed as an unconscious, learned self-soothing mechanism. It stems from childhood experiences where a person’s brain learned to find calm and emotional safety through the mouth. 

It originally began as a classic psychoanalytic theory. Sigmund Freud believed that oral fixation is rooted in the oral stage of psychosexual development where infants explore the world and self-soothe primarily through their mouths. However, modern psychology has largely moved away from Freud’s psychosexual framework and views oral fixation instead through the lens of behavioural psychology and neuroscience. 

All in all, Nicholas likes having things in his mouth, especially Euijoo’s dick. Sue him. Euijoo tastes really good, and yeah Nicholas is definitely biased but he doesn't give a rat’s ass. 

When Nicholas pulls off of him, a string of spit comes away with his bottom lip. He smiles and leaves a soft kiss on the head of Euijoo’s dick causing it to twitch in his hand. Changing his method to slow strokes as he stares Euijoo right in the eyes, licking his lips purposely. 

“Am I doing good?” he asks, knowing damn well what the answer will be but it never hurts to hear it out loud from time to time. 

“Shit, baby—” Euijoo stutters, his hips jerking forward, chasing Nicholas’ hand. “You're doing amazing. Spectacular. I love you.”

Satisfied with the answer, Nicholas springs back into action and takes Euijoo back into his mouth but not closing his eyes this time. He wants to watch Euijoo crumble beneath his hands.

Euijoo gasps and whines, squeezing his eyes shut and throwing his head back repeatedly. He looks so pretty like this, Nicholas feels himself throbbing in his pants. Euijoo, ever the gentleman, is fighting hard against the urge to just fuck into Nicholas’ mouth, he sees it in the way Euijoo’s legs shake slightly with restraint. It's really sweet, but Nicholas has told him many times that Euijoo can just use and do whatever he wants with Nicholas, he's just happy to be involved. 

"Nicholas. Hyung. Please." 

Nicholas shamelessly moans around the dick in his mouth and Euijoo almost topples over. See, his boyfriend never calls him that, despite being the younger one in the relationship, unless he's really freaking desperate. 

Nicholas’ hand tightens around Euijoo and starts working him closer to the edge with some new found motivation. Euijoo is letting out a handful of very creative curses and before they both know it Euijoo is coming down Nicholas’ throat and at the same time Nicholas also finishes in his pants on his own.

Conditioning Phase: Initial Pairing Trial

Day 3

Objective:
Assess formation of association between neutral stimulus  and unconditioned response.

Procedure: Neutral stimulus was introduced immediately prior to direct researcher–subject interaction in a shared domestic setting. Presentation was kept casual and non-anticipatory to avoid expectation bias. Temporal pairing was maintained consistently across interaction onset.

Observations:
Subject displayed immediate attentional shift toward researcher upon entry. Verbal communication was briefly interrupted by physiological response indicators (speech delay, altered breathing patterns, increased focus on researcher presence).

Subject did not initially register or question the neutral stimulus, instead prioritizing continued interaction.

When stimulus was introduced, subject maintained engagement without disruption, suggesting low interference with ongoing behavioral response.

Results:

• Response to neutral stimulus alone: Not established

• Response to researcher presence: High

• Behavioral compliance: Elevated

The bell is used four times this week but they have sex five times, though the fifth time Nicholas couldn't anticipate. They were having a big fight over something Nicholas doesn't even remember anymore, their fights usually are about stupid shit anyway. Nicholas as always was pushing Euijoo’s buttons and he just snapped, bending Nicholas over the kitchen counter and letting his anger out on him that way. 

The following day was spent deep cleaning the kitchen but it was so worth it and Nicholas would definitely do it again. 

Report: Week #1

A total of four successful pairings were completed during Week 1.

No conditioned response has been conclusively established. However, subtle behavioral changes suggest the subject may be beginning to associate the stimulus with subsequent events.

Further observation required.

Researcher’s notes: Subject remains unaware of the experiment. Continue conditioning schedule.

Additional notes: stop leaving notebook unattended. Subject nearly found it on Thursday.

⋆˚꩜｡

Nicholas is sitting in his car in the parking lot outside Euijoo's band practice studio, fifteen minutes early.

The engine is off, the evening air is beginning to cool, and Nicholas has one foot propped up against the edge of his seat while he absentmindedly sucks on a lollipop.

To kill time, he's on FaceTime with Yuma and Maki.

“This is so surreal. I’m going to be speaking to an honest-to-God serial killer.” Yuma says, though his camera is pointing at the ceiling because his phone slid down and he's been too busy trying to get Jo’s cat from under the bed to position his phone correctly. “The psychology is pretty fascinating, well biology really – come here, biscuit, pspsps – Brain scan research shows clear differences in the amygdala and the supermarginal gyrus of a signature killer – please come out or your dad will never let me babysit you again—”

Maki stares at his screen with a look of profound confusion. "Could you say that again in a language normal people understand?"

Nicholas pulls the lollipop out of his mouth to speak. “They lack the ability to feel empathy,” he points the lollipop at the camera, "there's also research suggesting some of them have a weaker sense of smell."

“Making it easier for them to deal with dead bodies?” Maki asks looking pretty horrified. 

Nicholas puts the candy back in his mouth, to ease the itch, and nods. 

“Can we talk about something else,” Maki says, his camera shaking a little as he twists his body around like he's suddenly convinced someone is in the room with him.”Taki is out of town tonight and I’m really scared right now.” 

Right on cue, Yuma finally reappears on screen. His hair looks like he stuck his finger in an electrical socket. There's a streak of sweat sliding down his temple and what appears to be cat fur stuck to his shirt.

"Aww," he coos. "Is little Maki scared without his boyfriend?"

Maki scowls. “Watch it, or I will tell your boyfriend that you scared his cat away.” 

Those two end up bickering for two more minutes before the phone call disconnects.

Nicholas stares at the dark screen for a moment before tossing his phone onto the passenger seat. The lollipop shifts between his teeth as he reaches across the dashboard for his notebook.

He's got exams coming up again so he's using every moment he can to study. 

At eight on the dot his phone lights up with a notification from Euijoo saying they're done and that he'll be right out. A smile forms on Nicholas’ face as he reads the message, he really can’t help himself. He's in love.

He quickly replies with a ‘😸👍’ and puts his phone away then throws the notebook to the backseat. The movement is so abrupt that it causes the bell in his pocket to chime. Right, he completely forgot he had it. He wasn't planning on using it today but he wouldn't mind making out with Euijoo a little bit, his lollipop was already all gone a while ago and he's been chewing on the straw this whole time now. Euijoo can keep his mouth busy instead. 

It's already the third week of conditioning and Nicholas is starting to notice the way Euijoo reacts very subtly to the bell sound. He doesn’t think the connection is strong enough yet but it's getting there.

One thing he's gotta say is that this whole thing has been so much fun. Having sex with Euijoo always is, if he could he'd quit everything and just do that for the rest of his life. Everything about Euijoo is so addictive that Nicholas sometimes thinks Euijoo was made in a lab created especially for him – some kind of Nicholas specific drug. 

The trunk is opened and Nicholas startles. He didn't even notice Euijoo approaching the car, too busy getting lost in his daydreaming of Euijoo fucking him.

Nicholas unlocks the doors from inside and Euijoo immediately slips into the passenger seat, wasting no time in leaning over and giving Nicholas his kiss. 

“Hey, baby. I missed you.” 

Nicholas blushes. He blushes because his boyfriend of three years tells him that he missed him. Yeah, he's beyond helpless.

“I missed you too.” Nicholas says back, a little breathless.

Euijoo smiles and puts his backpack down in between his legs. The small moment Euijoo’s eyes aren't on Nicholas, he takes the opportunity to give himself a very small slap to the cheek to pull himself together.

Nicholas clears his throat, regaining some composure. “Were you guys practicing Total Eclipse of the Heart ?”

“No.” Euijoo replies swiftly, avoiding Nicholas’ gaze. 

“Juju, you're a very bad liar,” Nicholas teases, leaning over the centre control and getting all up in Euijoo’s face like an annoying cat that doesn't understand the concept of personal space. “I could hear Yunjin sing her heart out all the way to the car.”

Euijoo sighs defeatedly and pushes his glasses back up with his knuckle. “Okay yeah we were.”

Nicholas laughs. “Why were you guys practicing our song?” 

Three years ago Euijoo invited Nicholas over to his dorm to watch a movie together, by that time they’ve been kind of skirting around each other for an embarrassingly long time with neither of them being brave enough to make the first move. They picked out a very random movie about some kid surviving middle school or something like that. Nicholas doesn't remember much because he was way too nervous about being alone with Euijoo to really pay attention. 

He’d been working up the courage to make the first move but Euijoo beat him to it, he kissed him right as the protagonist of this stupidly funny movie started singing Total Eclipse of the Heart. They ended up making out until the end of the movie and the next day Nicholas asked Euijoo to be his boyfriend. 

Hence, that song being their song. It was all just an inside joke at first but now they even decided to play it at their wedding one day. 

Euijoo swallows nervously. “No reason at all.”

“I’ll just ask Eunchae, she can’t keep secrets even if her life depended on it.”

“She doesn't know anything.”

Nicholas perks up, leaning closer again trying to push the right buttons until Euijoo spills the beans. “So there is a specific reason why you guys are playing it.” 

Euijoo doesn't take the bait. He just looks at him, his eyes warm with fondness and suddenly leans in again, lips brushing against Nicholas’. 

Nicholas is taken by surprise for a moment but quickly catches up and tilts his head, deepening the kiss. Euijoo parts his lips and their tongues slide together, the softness the kiss carried two seconds ago quickly vanishes and with each press of their mouths, the kiss becomes more and more heated.

Nicholas slides his hands up Euijoo's arms all the way to his shoulders, feeling the warmth of his skin radiating through his thin shirt. He leans in closer and closer until he's halfway over the control centre. Euijoo reaches for Nichola’s hip and gives it a small tap to tell him to climb into his lap.

So he does and the bell rings in his pocket as he swings his leg over. Immediately a small, obvious shudder runs through Euijoo’s body. There it is.

It's slightly cramped with this new position so Nicholas reclines the seat a little for Euijoo while he puts his hands exactly where they belong; on Nicholas’ waist. Euijoo’s glasses, which have fogged up from the heat of their proximity, hang crookedly on his nose. Nicholas lets out an airy chuckle and nudges them back into place before returning to the kiss. 

Nicholas kisses like a man starved. He can never get enough of Euijoo, always wants more more more and Euijo lets him take take take until every piece of himself belongs entirely to Nicholas. 

Euijoo abandons his lips and moves down to his jawline then further down to his neck. He leaves a trail of wet kisses all over Nicholas’ neck and each kiss plucks a louder moan out of him. 

Seventy seconds that's how long Nicholas can go without Euijoo’s lips on his, it has been eighty now. Nicholas grabs Euijoo’s face with both hands and tilts his face up again to slot their lips together. It's hard and messy. Euijoo arches against him, palms resting just slightly above his ass pulling his body even closer to Euijoo than it already is. 

Nicholas goes for the belt and right as he's about to unbuckle it, someone knocks loudly against the passenger side window. They both freeze in their tracks, like they’ve been doused in ice cold water. 

They can't see who it is because the window is all fogged up which means the person outside knows what they’ve been up to if they couldn't already tell by Nicholas sitting in Euijoo’s lap. 

The window slides down, revealing their mutual friend and front woman of Euijoo’s band, Yunjin. 

She stands there with a knowing smile. “Hey guys. Sorry to interrupt your little public indecency thing here but Euijoo you forgot your phone.” 

Euijoo and Nicholas both look up at the phone she's holding, it even lights up with a notification showing Euijoo’s lock screen of a picture of the photobooth strip they took in London earlier this year.

“Thank you, Yunjin.” Euijoo mumbles, head hanging down in shame and not even looking Yunjin in the eyes as he holds out his hand and she places the phone in it. 

“Great,” Yunjin chirps happily. “I’ll let you get back to,” she wiggles her hands around, “this.”

Nicholas slides the window back up and bursts out laughing, throwing his head back and all. Euijoo just hides his face in his palms, groaning in misery. 

“This is now the third time we’ve been caught almost having sex by one of our friends.” Nicholas says, amusedly, playing with Euijoo’s hair.

Euijoo whines. “That is so embarrassing. Nichol, we have a problem.”

“No we don't.” Nicholas rolls his eyes.

“How come we never catch Maki and Taki, Jo and Yuma or Yunjin and Chaewon like this.” 

Nicholas doesn't have a real explanation for that. He never really thought about it until Euijoo now pointed it out. 

“We have too much sex in places people shouldn't be having sex, Nicholas.”

Euijoo might have a point but Nicholas doesn't really care. “But that's what makes it so hot,” Nicholas says, pinching Euijoo’s cheeks playfully. “The thrill of whether someone will catch you or not.” 

“You are a freak.” 

“Oh, I’m a freak?! What was it that you said to me two days ago during sex?” 

Euijoo blushes again. “That was—”

“Baby, I’ll fuck you as many times as it takes to put a baby in you.” Nicholas mimics Euijoo’s voice in a really dramatic manner. “Someone with a breeding kink isn't allowed to kink shame anyone.”

Euijoo wheezes out of embarrassment. “I said that in the heat of the moment! You can’t hold the things I say when I’m balls deep inside you against me outside of the bedroom.” 

“I love you. You are so funny,” Nicholas sighs with delight. He really enjoys teasing Euijoo. “Besides, I bet I’d look so hot pregnant. Can you imagine me with the pregnancy glow, the cute baby bump and the—” Nicholas pauses for a second, looks down then back up, “Euijoo, did you seriously just get hard again?”

⋆˚꩜｡

Report: Week #3 

Conditioning process has progressed substantially beyond initial expectations.

The bell now appears capable of eliciting anticipation without immediate presentation of the unconditioned stimulus.

Subject has begun demonstrating behavioral changes immediately following stimulus presentation, including:

• Increased attentiveness

• Visual orientation toward researcher

• Interruption of ongoing tasks

• Positive emotional response

Further testing required to determine whether a conditioned physiological response can be elicited by the bell alone.

⋆˚꩜｡

Eight weeks later, Nicholas finds himself on campus, occupying his usual corner table in one of the air-conditioned cafés between lectures. The afternoon rush hasn't started yet, leaving the space pleasantly quiet save for the occasional hiss of the espresso machine behind the counter.

A stack of readings is spread out in front of him. He's halfway through an article, absentmindedly chewing on the end of a pen while his eyes skim over paragraph after paragraph. Every now and then he underlines a sentence or scribbles a note in the margin, but for the most part he's operating on autopilot. Read. Highlight. Turn page. Repeat.

"Wang Yixiang," Yuma singsongs as he drops into the empty seat across from him. "I know what you did."

Nicholas slowly lifts his eyes from the article and glances around the café searching for another Yixiang that Yuma could possibly be addressing. His gaze drifts from table to table before eventually returning to Yuma.

The pen slides out from between his teeth.

"I have absolutely no idea what you're talking about."

Yuma's grin widens. "You are such a little freak, Nicholas—I mean, I always knew you were weird, but this? This really takes things to another level."

Nicholas reaches for his drink just as Yuma does the same and he slaps his hand away. "Again," he says, pulling the cup closer to himself. "No idea what you're talking about."

"Okay." Yuma settles deeper into his chair. "Let's rewind to yesterday. Euijoo and I went to the movies. We got tickets. We got snacks. We found our seats. Everything was completely normal. The previews start playing and nothing unusual is happening. Then in one of the trailers, there's the sound of a bell,” Yuma leans forward, “guess what happened next? Not only does Euijoo choke on a piece of popcorn but his entire body locks up. He jumps out of his seat so fast that I think he's having some kind of medical emergency. The lights are still on so imagine my surprise when I catch a glimpse of a very obvious problem in his pants before he practically sprints out of the theater."

Nicholas' jaw drops. Yuma immediately takes advantage of his stunned silence and snatches his drink.

"It took me a while to figure it out," Yuma says before taking a victorious sip. "At first I was completely confused. There wasn't anything remotely suggestive on the screen and you weren't there but then I remembered a conversation I had with you a few months ago."

Nicholas huffs out a breathless, disbelieving laugh. "I can't believe it actually worked."

Yuma laughs around the already bitten straw in his mouth. “You really pavlov’d your poor boyfriend into getting a hard on at the sound of a bell. Freud would've loved you.”

Nicholas has Yuma completely tuned out. He gathers all of his things in a frenzy, shoves everything in his backpack not even bothering to put his pens correctly into the little pen pouch Yunjin made for him. 

"Dude, where the hell are you going?" Yuma asks as Nicholas zips his backpack shut. "We have class in ten minutes."

“You’ll lend me your notes later. I gotta go.” Nicholas says in a hurry, already halfway through the door. 

Nicholas runs back to his apartment, quite literally sprints like he's being chased by someone. Usually it takes around twenty minutes to get home, he makes it there in ten which is also why he is completely out of breath by the time he gets to the front door of the building.

He makes it approximately halfway up the first flight of stairs before collapsing onto one of the steps and sitting there like a Victorian woman suffering from a mysterious illness.

To his disappointment, Nicholas finds the apartment empty with no Euijoo in sight like he had hoped. He closes the door behind him and drops his backpack onto the floor before making his way toward the couch then lets himself collapse dramatically onto the cushions, sprawling across the entire length of the couch with a heavy sigh trying to remember where Euijoo could be. 

He doesn’t have class because Euijoo's Thursday schedule consists entirely of morning lectures, doesn't have band practice because those are only every other day at night and Euijoo doesn't really go out with his friends so that only leaves one more option; grocery shopping. 

It's Grocery Thursday as Euijoo likes to call it where every Thursday he goes grocery shopping even though he hates doing that because he gets very easily overstimulated. Plus the store he always goes to has a habit of reorganising everything from time to time and it drives Euijoo mad when has to wander around the store trying to look for a specific thing but he still manages to come home with every single item on the shopping list. 

Whereas Nicholas would probably get distracted and forget to buy half the things again. It has happened too many times before. 

Nicholas groans and throws an arm over his eyes. Technically he skipped class for nothing because it will take Euijoo about an hour to come back home but it's fine, he'll just take a shower and nap until then. 

The shower gets taken but the nap, however, never happens. 

Somewhere between drying his hair and crawling into bed, Nicholas makes the fatal mistake of opening his phone. One meme from Maki turns into another, Nicholas then sends one back and Maki sends something even dumber, which forces Nicholas to spend the next five minutes searching for an equally stupid response.

Before he knows it, nearly an hour has disappeared.

Nicholas is lying sprawled across the bed on his stomach, kicking his feet absentmindedly behind him while laughing at something Maki sent. He's so absorbed in the conversation that he barely hears the rattling of keys against the front door until the lock clicks.

He practically throws his phone across the mattress and scrambles off the bed. One of his feet gets tangled in the blanket and he nearly faceplants onto the floor trying to get off but he catches himself at the last second, stumbles forward, then immediately takes off running.

"Euijoo!"

He yells happily down the hallway, barreling around the corner at full speed. Euijoo barely has enough time to look up before Nicholas crashes directly into him.

"Whoa—!"

Euijoo staggers backward a step but somehow manages to keep both his balance and his grip on the groceries. His free arm automatically wraps around Nicholas' waist.

"Nichol?" Euijoo says, blinking down at him in confusion. "What are you doing here already?"

Nicholas ignores the question, reaches up to pluck the baseball cap off Euijoo's head, hangs it neatly on the hook by the door and threads his fingers through Euijoo's soft hair.

"I skipped," Nicholas says, his fingers continue combing through the dark strands and making a complete mess out of it. "But that's not important. Come with me."

"Uh, okay." Euijoo slips out of his shoes. "I'll be right there. I just have to put the ice cream away first before it melts."

Nicholas is already halfway down the hallway.

"Now, Euijoo!"

Euijoo looks down at the grocery bag containing the ice cream, then toward the hallway, then back at the ice cream.

"But the ice cream."

"Euijoo!"

Euijoo sighs.

"Coming!"

Nicholas grabs both of Euijoo's wrists and drags him to the edge of the bed.

"Sit."

Euijoo obeys, though not without looking concerningly suspicious. "What's going on?" he asks, glancing around the room.

Nicholas smiles. "Close your eyes."

"Why?"

"Because I said so." Nicholas crosses his arms over his chest and tries to look authoritative but unfortunately, the effect is somewhat ruined by the fact that he's practically vibrating with excitement.

Euijoo closes his eyes then opens them again immediately. "Okay, but you're not allowed to punch me in the face."

Nicholas clicks his tongue. “I won’t punch you, dumbass. Just keep your eyes closed until I tell you to open them.”

Euijoo’s eyes are closed again and Nicholas stays standing in front of him for a few seconds to make sure he actually keeps them closed. He does. Nicholas expected nothing less.

He giddily tiptoes over to the dresser, opens a drawer and very carefully pulls out the collar to which he has attached the bell to. The thing is part of his halloween costume, he's going as a cat and Yuma will be his witch. He puts it on without moving the bell and tiptoes back in front of Euijoo, who obediently keeps his eyes closed.

Nicholas is nervous, he's about to witness if the experiment actually works. He flexes his fingers to get the stiffness out of them and leans closer towards Euijoo. With a few shakes of his head the bells clinks, and Euijoo gasps. Nicholas drops his eyes down to Euijoo’s crotch area and to his absolute delight he finds Euijoo with a hard on. 

“What the fuck?!” Euijoo gasps again, this time his eyes snap open and he's wearing an expression of pure confusion.

Nicholas squeals and jumps around on the spot, the bell ringing some more and Euijoo bends over, groaning. 

“Oh my god. It actually worked.” 

Euijoo sits straight up again and eyes Nicholas with wide eyes. “Yixiang. What the hell have you done to me and why are you wearing a collar?”

Nicholas bares his neck showing it off. “It's part of my Halloween costume — Wait let me show you.” He reaches back into the drawer, pulls out the cat ears and slides them onto his head. “Ta–da. I’m going as a black cat.”

Euijoo’s pupils blow unmistakably wide, his breath slightly catching in his throat and Nicholas wears a proud smug smile on his face. He knew Euijoo would love the collar and the ears. 

“How do I look?” Nicholas asks, striking a pose. 

Euijoo looks like he's about two seconds away from salivating, his eyes have gone a little dazed.

“Euijoo! Concentrate!,” Nicholas snaps his fingers in front of his boyfriend’s face, “I asked you a question and I would like an answer.” 

Euijoo shakes his head to clear his mind. “All the blood in my body literally rushed into my dick. I can't form a proper thought.”

“So think with your dick then that's what you do all the time anyway.” Nicholas huffs offendedly, pouring it on thick, and rolling his eyes.

“Come on, baby,” Euijoo whines. “You know you look beautiful.”

Of course Nicholas does but that doesn't stop him from being a sucker for compliments anyway, especially from Euijoo. Floating high up into the clouds whenever he gets called beautiful, pretty, handsome or sexy by his boyfriend. 

“Great,” he claps his hands together enthusiastically. “Now take your pants off.”

Euijoo complies immediately, seemingly having already forgotten about the fact that he got a boner from hearing the bell but without any blood in his brain, thinking coherently must be a difficult task.

Disappointment rolls through Nicholas when he finds that Euijoo isn't wearing one of his nerdy boxers today.

Together they shuffle further up the bed and Nicholas coaxes Euijoo to sit back against the headboard, then pulls off his own shirt before climbing into Euijoo’s lap. From here, he can see the way Euijoo’s chest rises and falls, the pink of his round cheeks and the hunger in his eyes that seems barely contained. 

Euijoo’s hands settle on Nicholas’ thighs but he swats them away immediately. “Nuh-uh, you're not allowed to touch me.”

“Nichol, please.” Euijoo breathes out, sounding like not being able to touch him is causing him a great deal of pain.

Nicholas coos and drags a featherlight finger over Euijoo’s clothed dick, earning a full body shudder and a beautiful moan. 

“You can go a while without touching me. I know you can, baby, because you're a good boy.” 

Euijoos lets out a pained noise but Nicholas swallows it up by bringing their lips together into a slow messy kiss and tasting the cherry coke Euijoo probably drank on his way back after sliding his tongue over his lips. 

Nicholas then moves his hips against the hard press beneath him, heat spreading through his body like wildfire at the thought of having that thing inside him soon. With every drag of his hips, Euijoo gasps into the kiss, and each sound fuels Nicholas to do it again, and again, until Euijoo is practically vibrating with restraint of not putting his hands on Nicholas and pulling him closer. 

The quiet noises they share into each other's mouths are like music to Nicholas ears, a beautiful symphony of their shared pleasure. 

Nicholas smirks against Euijoo’s mouth before biting into his lower lip. Euijoo whimpers at the sting and Nicholas feels it vibrate straight through him. He then pulls away, not too far, and trails his mouth along Euijoo’s jaw, leaving kisses all the way down to the slope of his neck. 

Nicholas lingers there, scraping his teeth against tender skin and sucking a hickey right into it. Euijoo's head falls back against the headboard, a wet sound slipping from his throat as Nicholas works another mark near his collarbone 

Stopping to admire his masterpiece, Nicholas can't help himself from leaning in again, pressing another kiss and another bite into Euijoo’s already flushed skin. He wants every inch of Euijoo's skin to wear to undeniable proof that he belongs to Nicholas.

Euijoo shudders, biting his lip, and Nicholas can feel his thighs trembling beneath him. “Nicholas,” he gasps, looking at him with desperate, pleading eyes.

Nicholas hums, cocking his head to the side, feigning cluelessness. “What's up, baby?”

“Nichol, please.” 

He soaks up the desperation in Euijoo’s voice, always so eager to touch him like not having Nicholas’ skin under his fingertips is the worst thing on earth. It gets to his already inflated ego but how is that his fault when Euijoo behaves like he’d beg on his knees if Nicholas asked him to.

Nicholas dips down to kiss Euijoo again, deliberately grinding harder as he does and the kiss turns messy instantly, with their teeth clashing, tongues sliding and both of them breathing like they can’t get enough of each other.

When they break apart to suck in some air, a string of spit connects them. Nicholas grins wickedly. “Should we get rid of these?” he asks, snapping the waistband of Euijoo’s boxes playfully.

Euijoo jolts, biting back a sound that makes Nicholas grin even wider. “I love how sensitive you are,” he teases, dragging his finger along the elastic, just barely dipping inside before pulling away again. 

Euijoo watches Nicholas’ every movement like he's hanging on a thread. His hands twitch where they're gripping the sheets, wanting to touch but he doesn’t dare move. 

“Such a good boy,” Nicholas murmurs, leaning down to press a wet kiss to the corner of Euijoo’s mouth, then another to his jaw. “I bet you're dying for me to touch you properly, hm?”

“Nicholas…” Euijoo breathes, voice rough with need. 

“What?” Nicholas’ hand brushes against the outline of Euijoo’s dick through the thin fabric. Euijoo’s breath catches, and Nicholas pulls back his hand, smiling. “Oh. Is that what you want?”

A frustrated whines escapes Euijoo and hides his face in Nicholas’ shoulder, mumbling, “Please.”

Nicholas’ heart swells up, Euijoo is so adorable, and he lets himself bask in the way Euijoo is turning to putty in his hands. He cups Euijoo’s face, coaxing him to look at him. “Say it properly.”

Euijoo’s lips are kiss-swollen, his eyes glassy and pupils blown wide. “Touch me,” he whispers, then when Nicholas raises a brow, he swallows and says louder, “Please, hyung. I need you to touch me.”

That little motherfucker used the one word that has Nicholas just as much bending backwards for Euijoo. Heat curls in his stomach and arousal thrums through his veins more intensely than before.

He kisses Euijoo while letting his hand travel down, skimming every inch of bare skin he can find, but instead of going where Euijoo wants him, he avoids it on purpose, sliding back up over his stomach again, then his ribs, feeling him shiver. 

Two can play at that game.

Euijoo's thighs tense up and his hips buck, hoping to chase the friction on his own but Nicholas plants a hand firmly against his chest to keep him still. 

“Beg a little more for me,” Nicholas murmurs, licking over the bite mark he left on his shoulder before bringing his lips back to Euijoo’s letting them hover over his. “Let me hear how much you want it.

“Please, baby. Please, please,” Euijoo whines into Nicholas’ mouth and Nicholas smirks against his lips. “I need you to touch me. I’ll be so good to you.”

“Okay, handsome,” Nicholas finally says after letting the silence stretch just long enough to keep Euijoo trembling with anticipation. 

He could keep pushing, keep teasing until Euijoo was begging with tears in his eyes but the truth is, he's growing impatient too.

Nicholas’ thumb strokes lazily just under the waist band and Euijoo’s hips jerk upward in desperation. Finally, Nicholas has decided that Euijo has suffered enough and slips his entire hand down and curls his fingers around the hard length and eases it free and Euijoo lets out a moan of relief. 

He shamelessly stares at the flushed, swollen tip where precum is already leaking out and the thick vein that he likes to trace with his tongue. Euijoo’s got a very pretty dick and even after three years the fascination with it hasn't disappeared one bit.

The moan Euijoo lets out is nothing short of sinful when Nicholas drags his thumb across the wet slit at the head and draws slow circles. “Fuck—Nicholas,” he gasps, voice breaking on the syllables. His fingers clutch at the sheets until his knuckles turn white and his lashes flutter.

Nicholas strokes again, longer this time, twisting his wrist on the way up so the pressure drags differently across the veins. Euijoo’s whole body twitches, hips jerking despite himself, chasing friction like he can’t help it. “God—” he groans, head falling back.

Nicholas leans closer, letting his breath graze Euijoo’s jaw as he whispers, “You’re dripping all over my hand.” He pumps a little quicker to emphasize the words.

A broken noise spills from Euijoo’s lips and his hips roll helplessly into Nicholas’ fist, chasing every movement. Nicholas’ gaze drops, captivated by the sight of the thick length sliding slickly through his hand, veins straining as more precum leaks with every stroke. He gives an extra squeeze just under the head, and Euijoo cries out.

Nicholas keeps the pace steady but slow enough to torment. Gliding smoothly now, wringing a couple of colourful curses from Euijoo. His back arching off the mattress, chasing more friction than Nicholas will give. 

Nicholas watches him with rapt attention, his chest tightening at how beautiful Euijoo looks undone like this. He squeezes a little harder near the base, dragging up slowly. 

“Nichol—fuck—so close—” Euijoo’s voice cracks, desperate now, every word pulled from the 

“That’s it. Come on, Juju, let go for me.” Nicholas’ tone is soft and coaxing, as his hand quickens just slightly, stroking him with a rhythm that’s finally enough.

The thread snaps and Euijoo’s entire body arches, his mouth falling open on a loud, unrestrained moan as his orgasm tears through him. Hot ropes spill over Nicholas’ hand and stomach, coating his skin as he works him through it with slow, milking strokes.

Euijoo shakes beneath him, squeezing his eyes shut while he rides out the aftershocks with whimpers that fade into exhausted groans.

Nicholas finally lets go of Euijoo’s dick, his palm slick and messy with cum, then sucks each finger off with wet lewd noises like he's tasting a delicacy.

Euijoo looks up at him, eyes hazy, lips slightly parted and the post-orgasmic flush painting his cheeks. Nicholas leans just slightly to the side, fingers brushing along the nightstand until he pulls out the familiar bottle of lube.

“You did so good, baby. You’ve earned your reward.” Nicholas says, slightly out of breath as his arousal is affecting him. 

Euijoo’s lips curl into a victorious smile like a guy who’s just been handed permission to eat a forbidden treat and Nicholas knows for a fact that he is that treat. He takes the bottle of lube carefully from Nicholas’ hand and sets it within reach, then slides his palms over Nicholas’ hips and pushes them up so that he can help him get out of his own clothes. 

When Nicholas is finally naked as well, Euijoo traces over his thighs, his hips, the small of his back, feeling the way Nicholas’ muscles tense up under Euijoo’s touch. 

Nicholas tilts his head, eyes dark with desire, watching the way Euijoo’s hands mold around him. It makes him feel both cherished and exposed.

Euijoo picks up the bottle of lube, uncaps it and pours some on his fingers before rubbing it between them to warm it. His other hand stays planted firmly on Nicholas, he’s pretty sure he's going to have an Euijoo-hand-shaped bruise tomorrow. 

He gives Nicholas a little tap on the hip, and Nicholas immediately lifts them slightly to make space for Euijoo to work his magic. Now it's Nicholas’ turn to shiver when Euijoo teases the most sensitive area around his entrance. 

“Ah…Euijoo…” His voice airy and filled with need.

Euijoo drags his finger teasingly over the rim just shortly before sliding inside. They’re not long or particularly thick like Nicholas’ but he knows how to use them, knows to make the best of what he’s got.

His fingers move in a slow rhythm, applying enough pressure to make Nicholas squirm, stretching him gently. Nicholas clutches Euijoo’s shoulders, nails digging into his flesh and leaving crescent moons in there. Chest heaving as he presses helplessly back against Euijoo’s hand and biting into his lower lip to suppress a whimper but failing.

“Y-yeah… just like that,” Nicholas moans airily, hips rocking with the gentle pressure of Euijoo’s fingers. 

Euijoo smiles softly, almost shyly, leaning closer so his forehead brushes Nicholas’ shoulder. He presses in a second finger and goes deeper, winning a deep whine from Nicholas. The slick warmth, combined with the careful teasing of his fingers, makes every nerve in Nicholas’ body pulse with anticipation.

Euijoo stretches, teases, and teases again, savoring the way Nicholas reacts, the shiver that ripples through him, the way his hips tilt involuntarily and the soft whimper that escapes his throat each time Euijoo curls a finger inside and drags it out.

Nicholas is utterly at his mercy. It’s overwhelming and he doesn't know what to do with himself. So his body reacts before his mind can stop it, hips lifting involuntarily, trying to escape the intensity of Euijoo’s touch but Euijoo’s free hand slides to his waist, gripping him tightly as he pins him back down again. 

“You can take it, beautiful,” Euijoo murmurs. There’s a crease between his brows, his face drawn with focus, like he’s pouring every ounce of concentration into the task of unraveling Nicholas.

And it’s working because he finds his prostate with ease, and Nicholas breaks. The moan that rips from his throat is loud and porn-worthy, his soul nearly leaving his body. Nicholas’ eyes flick up, and Euijoo’s gaze meets his. The world seems to still and Nicholas swears he hears wedding bells.

“Baby, I’m ready—” he hisses out, voice breaking as Euijoo’s fingers brush over another unbearably sensitive spot.

Euijoo stills immediately, searching his expression. “Are you sure?”

Nicholas needs him now. He nods quickly, biting down on his lower lip to smother another shameless moan. Euijoo then lets his fingers slip free with agonizing slowness, leaving Nicholas trembling and clenching around nothing. 

Euijoo licks his lips, then says, “Okay then. How do you want me?”

Nicholas takes a shaky breath, eyes never leaving Euijoo’s. “Just… like this. Stay like this, I’ll ride you.”

He steadies himself with a palm pressed flat against Euijoo’s chest, feeling every thud of his heart against his palm, a heart that was made to beat solely for Nicholas. His other hand wraps around Euijoo’s dick, guiding it down to where he needs it most. The head nudges against his entrance, and Nicholas hisses softly at the first touch.

Euijoo swallows, eyes locked on where they’re joined and his fingers flex against Nicholas’ hips like he wants to pull him down in one go, but he waits, letting Nicholas control everything. 

Slowly, Nicholas lowers himself, every inch pushing past his rim, making his breath catch at the stretch. He pauses halfway, gasping, thighs quivering and his head falls forward, lips brushing Euijoo’s collarbone as he struggles to breathe through it.

“Easy,” Euijoo murmurs encouragingly, stroking his thumbs over Nicholas’s hipbones in soothing circles. “You’re doing so good, beautiful.”

The praise lights up fireworks in his veins and he takes another breath before rolling his hips down further, Euijoo’s cock sliding in deeper and dragging against every nerve inside him. His mouth falls open on a choked moan.

Finally, Nicholas is fully seated, every inch of him trembling with the overwhelming fullness. “Jesus,” he pants, biting his bottom lip so hard it stings. “You’re… fucking huge.”

Euijoo chuckles softly. “You’ve been taking my dick for three years. Shouldn't you be used to this by now?”

“Shut up,” Nicholas grits through his teeth while he's adjusting. 

In the meantime, Euijoo leaves soft kisses down Nicholas’ neck and Nicholas truly feels like he's on cloud 9. Nicholas lifts himself slowly before sinking back down again. The drag makes his toes curl and his moan comes out high and unrestrained. They both moan into each other’s mouths, lips ghosting over each other nearly touching. 

Euijoo is in his fucking lungs it feels like, Nicholas can't breathe. In his mind he counts to three before he does it again, lifting and sinking. Every shift of Nicholas’ hips pulls another sound from both of them, a mix of sharp curses, bitten-off whines, and low moans that vibrate against their skin when they lean close. 

Nicholas rolls his hips again, slower this time, savoring the stretch and the way Euijoo’s cock stirs deep inside him. The sound that slips out anyway is a helpless whimper, breathless and needy.

“Fuck…” Euijoo groans, voice guttural, as the grip on Nicholas’ waist tightens, fingertips pressing bruises into his skin.

Nicholas finds a rhythm and at one point, caught up in the haze, he gasps out that Euijoo’s allowed to move. The second the words leave his mouth, Euijoo thrusts up to meet him, and Nicholas’ soul leaves his body. The force drives him forward, collapsing against Euijoo’s shoulder, nails digging into his biceps. A raw, guttural moan tears from both their throat, so loud they will definitely get a noise complaint from their neighbours. 

“Ju—ah—Euijoo, wait—”

“What do you need?” Euijoo mumbles into Nicholas’ skin but he doesn't relent.

Nicholas wants to speak but replies with a moan instead when Euijoo thrusts back up again. He tries again. “I’m getting tired”

Euijoo scoffs mockingly but it's just meant to rile Nicholas up. “Your highness getting lazy, hm? Wants to just lay there and have me do all the work.” 

Nicholas doesn't get the chance to say anything because Euijoo flips them over. Now, hovering above Nicholas, he flashes him a charming smile and Nicholas brushes the damp strands of hair away from Euijoo’s forehead. He leans into the touch, eyes searching Nicholas’ face.

“You are so beautiful.” Euijoo says so genuinely it makes Nicholas want to punch him in the face, he's high on endorphins.

“Thank you,” Nicholas replies with a flushed smile. 

He untangles himself from Euijoo’s embrace, to roll onto his stomach, pressing his chest into the sheets and pushing his hips back, grinding against Euijoo’s pelvis. The sharp groan it pulls from him vibrates down to Nicholas’ bones. 

The blunt pressure of Euijoo’s cock nudges against him, and the anticipation sends sparks shooting up his spine. Backshots from the hot nerd hovering above him, life couldn't get any better than that.

Euijoo settles behind him and presses his chest to Nicholas’ back. He kisses his nape while pulling his hips back to line himself up before pressing in deep and stills. His hands slide up Nicholas’ sides before curling tight around his waist. When he starts to move, it’s careful at first because he knows Nicholas is a lot more sensitive in this position. 

Two short minutes later Euijoo successfully finds Nicholas' prostate, making his whole body jolt and his mouth fall open on a sob. Nicholas twists his head just enough to glance back, eyes glassy with unshed tears. His lips tremble around the words. “You’re making me feel so fucking good. You’re perfect.”

Euijoo groans deep in his chest, hips rolling forward with a thrust harder than before, as if he can’t hold himself back anymore. Nicholas yelps, raking his nails down their bedsheets as his back arches. Euijoo shudders at the sight, his rhythm stuttering for a moment before he finds it again, determined to drag every beautiful sound out of Nicholas.

He succeeds, of course. Nicholas moans and sobs into the sheets, high-pitched and raw. Every push drags against his most sensitive spot, pleasure so intense his body feels like it’s on fire. Nicholas can barely breathe, but he can’t stop moaning Euijoo’s name.

Euijoo groans raggedly, his thrusts gaining force, the sound of skin against skin echoing filthily through the room. Nicholas can barely hold himself up anymore, his arms are shaking and he has to press his cheek against the spit and tear damp pillow. 

“Euijoo—ah—fuck—” His sobs break into hiccuping gasps, the words spilling without thought. “It’s too good—I can’t—oh god, you’re so deep, so big—”

Euijoo grunts like the words punched the air from his lungs, doubling over and pressing his forehead to Nicholas’ back, fingers digging into his hips. 

Nicholas gasps when Euijoo slams right against his prostate. “Fuck! Right there—don’t stop, don’t stop, please!” He’s almost screaming now, nails tearing into the mattress. “You’re doing so good—oh god—”

Euijoo nuzzles his face right behind Nichlas’ ear and nips at it. “Tell me you want it. I need to hear you say it.”

“I want you—fuck—want you to cum in me, fill me up, please—”

Euijoo buries himself as deep as he can go with a strangled moan and cums right on the spot. His release floods hot and thick and the sensation pushes Nicholas right over the edge, his body seizing as his cum streaks the sheets beneath him. His cock drags uselessly against the sheets and collapses forward. Euijoo holds him from behind, still buried deep.

They’re both gasping, soaked with sweat, clinging to each other as the high gradually begins to fade. Euijoo presses soft kisses to Nicholas’ shoulder, his temple, anywhere he can reach, whispering sweet nothings into his damp skin.

⋆˚꩜｡

Final Report

Hypothesis:
If a specific bell sound is consistently presented immediately before moments of physical affection and intimacy, the subject will eventually exhibit signs of anticipatory arousal upon hearing the bell alone.

Results:
The hypothesis was supported.

By the conclusion of the experiment, the subject consistently demonstrated anticipatory responses following presentation of the bell stimulus, even in the absence of the unconditioned stimulus. These responses included increased attentiveness, proximity-seeking behavior, and physiological signs of arousal.

The conditioned response became sufficiently reliable that the subject would often seek out the researcher immediately after hearing the bell.

Conclusion:
The neutral stimulus was successfully transformed into a conditioned stimulus through repeated pairings with the unconditioned stimulus.

The subject has successfully been Pavlov'd.

Researcher’s notes:
Following the disclosure of the experiment, the subject responded with unexpected enthusiasm. Rather than expressing concern over being unknowingly used as a test subject, he described the premise as "hot" and immediately inquired about the possibility of future experiments.

This response was not anticipated and raises several questions regarding the subject's judgment. Subject may have a few screws loose.

The subject also expressed particular fondness for the collar with the bell and requested that it remain in regular use in the bedroom.