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Shoto is used to walking in on Katsuki and Izuku in a myriad of situations. Mid-argument over which movie to watch for their weekly movie nights. Mid-water fight in the kitchen of their shared apartment. Even mid-fire in the kitchen once, a pot of blackened something on the stove. (Izuku hasn't been let back in there since.)
But when Shoto arrived home from work, toeing off his shoes and dropping his keys in the plate, he didn't expect to walk in to see Katsuki's face buried between Izuku's thighs.
Eyes wide, Shoto froze in the genkan. Surely this was some fever dream, some mirage—the thing he didn’t let himself think about when it got too late at night and his boxers grew uncomfortably tight.
But no, there they were.
Izuku, face flushed a pretty pink as he bit down hard on his lip, head thrown back and both hands gripping Katuski’s head tightly to his crotch. Even though he was trying to muffle it, though, Shoto could clearly hear little whines and moans slip through as Katsuki’s head moved-
Clearly experienced with what he was doing.
Shoto swallowed. He should- Leave. Or let them know he’s there. Or something.
But both feet are glued to the floor, his eyes stuck on that bobbing head of blond spikes, mussed by those scarred fingers.
Shoto wants to suck on those fingers. No, that’s not right. He wants Izuku to jam those fingers so far down his through Shoto chokes, held down and unable to do anything but take it- God, the number of times he’s dreamt of it since high school, that strong little body holding him down, taking and taking and taking-
Of course, when Katsuki and Izuku finally got together, Shoto filed those thoughts away. Those are his best friends. They deserve to be happy, after all.
But now… They look like a wet dream, Izuku sprawled across the couch, panting and moaning—still fully clothed on his upper half, but his boxers haphazardly dangling off his ankle.
“Yeah, you like that, nerd?” Katsuki growls, and Shoto swallow as a hot pulse of arousal goes straight to his dick. God, that voice, that wet rasp to it…
Would he sound the same after Shoto fucked his throat?
Shoto shakes the thoughts away, watching Katsuki’s shoulder flex—his body is still covering too much of Izuku for Shoto to see much, but the way his arm is moving…
He’s probably fingering open Izuku’s sweet little cunt.
Shoto imagines it. Would it be as hot and tight as he dreamt? Sopping wet, just waiting to be fucked and filled and-
“You like the idea of it, don’t you?” Katsuki continues, and Shoto swallows again, hard, pressing a hand to the front of his pants. “Getting caught—your precious little Shoucchan walking in on you like this.”
Shoto bites back a whimper at that nickname coming off of Katsuki’s tongue in that voice. Shoto wants to kiss that name off his lips. He wants to suck on Katsuki’s tongue. He wants to be fucked. But he stands there instead, frozen in place.
His response is nothing compared to Izuku, though, whose back arches wildly as a sob escapes his lips. “Kacchan- Kacchan, please-”
“Oh, so you really want to be caught, do you?”
Shoto can’t see Katsuki’s face, but he can hear the smug little lilt to his tone, can imagine the smirk.
“What, you want Shoucchan to come back from work, see me fucking destroying your sweet little cunt on the couch? What do you want him to do, hmm? Lick those cute little sounds out of your mouth? Or maybe he’ll fuck your throat instead, would you like that, huh?”
Izuku makes a sound like he’s dying, and Shoto grips himself harder through his pants. Oh, he’s going to hell for this.
“Or do you want him to go straight for the prize instead?” Katsuki must to do something wicked with his fingers because Izuku arches off the couch, half-screaming as he writhes on Katsuki’s fingers. The smirking blond doesn’t stop, doesn’t slow down, doesn’t grant the greenette any mercy. “Want him to go for your slutty little cunt, just dripping at the idea of being filled like the whore you are? Maybe he’ll suck on your cute little clit. Maybe he’ll fuck you dumb on his fingers. Or maybe he’ll just take advantage of all the work I’ve put in and just fuck you. You want that? You want Shoucchan to fuck you ‘till you’re screaming?”
Shoto swallows, pressing a hand against the wall. The filth dripping from Katsuki’s mouth—he wants to. He wants to join them, wants to- wants to do all of that.
“Please,” Izuku begs, head thrashing back and forth. “Please, Kacchan– nngh, pl- oh, please.”
“What do you want, baby?” Katsuki’s tone drops further, and the wicked edge to it makes Shoto’s stomach curl. “Use your words.”
“Please- oh, there, Kacchan, please, don’t- nngh, oh, don’t st- op,” Izuku hiccups, tears streaming down his face now as he opens his eyes, looks down between his legs and-
They make eye contact, green locking on mismatched eyes. Izuku’s eyes goes wide, then he throws back his head with a scream, twisting wildly as he comes, and those pretty little moans as Katsuki doesn’t stop, keeps finger-fucking him through the overstimulation.
“Shou- Shoucchan,” Izuku cries as Katsuki turns, and that smirk-
Shoto almost comes in his pants.
“You coming or not, IcyHot?”
Shoto’s never moved so fast in his life, stumbling to the living room, reaching out to trace his fingers down Izuku’s tear-streaked cheeks.
“Sho, Sho, Sho,” Izuku chants, his green eyes beginning to fog over as Katsuki continues to twist his fingers and now-
Now Shoto can see the full picture, can see Izuku’s legs spread wide, the green pubes wet with spit and slick and who knows what else, and- Katsuki. Four fingers deep in Izuku’s cunt, fucking him mercilessly, twisting cruelly and-
Shoto wants those fingers in his ass, wants to be spread open, wants-
“Sho, please, nngh- oh, right there, please- Sho, can I-” Izuku babbles, tossing his head as Katsuki twists his fingers.
“You can.” The words slip past Shoto’s lips. “Whatever you want.”
“No, no, use your words,” Katsuki taunts, and Shoto doesn’t know what he’s allowed to do, but they’re here, so he takes it- Leaning forward and stealing Katsuki’s lips.
Katsuki doesn’t hesitate in kissing him back, and it’s- it’s wet and hot and spins Shoto’s head as Katuski bites as his lips, then licks straight past them, coaxing Shoto’s tongue out of his mouth to suck on it. Shoto’s never wanted to come so badly in his life, and this is-
This is Katuski, whose free hand tangles in Shoto’s hair, yanks him back with a bolt of pain that goes straight to Shoto’s cock. He can’t help the whine that spills past his lips, and Katsuki smiles in a slash of white teeth.
“Shoulda known you’re just as much of a slut for pain as the damn nerd.”
Shoto doesn’t have time to respond, because Katuski’s diving back in, and it’s hot and wet and sloppy and Shoto almost doesn’t notice when Izuku’s hand clumsily paws open his pants and drags out his hard cock.
Almost.
Shoto hisses at the touch, biting hard on Katsuki’s lip-
“You’re hard,” Izuku whines, and Shoto breaks away from the kiss to see Izuku staring at his cock, gently tracing his fingertips over it. “Oh- Please- please, can I- nngh, suck?”
Shoto wants to fuck his mouth until he cries.
“No.” Katsuki bats away Izuku’s hands, and Shoto almost cries. Those pink, bitten lips look like a dream, and Shoto knows that Izuku would look so pretty choking on his cock. “No,” Katsuki continues with an evil little smirk that makes Shoto’s dick twitch. “What’s going to happen is that IcyHot over here is going to fuck your cunt sloppy while I finger him open. Don’t care if he comes inside of you, because then I’m going to fuck him until he cries, until he can’t move.”
Shoto’s brain whites out into a haze of yes yes yes, he wants it, and Katuski guides him with surprisingly gentle hands between Izuku’s legs, drawing out his fingers in the process.
Izuku whines as the loss, writhing on the couch cushions. “Sho, please, I’m so empty.”
“Slut,” Katsuki says affectionately as he reaches around Shoto, pumping his cock with fingers slick from Izuku’s pussy. Shoto slams his head back, moaning at the feeling—Katsuki’s hand is hot, slick with sweat and slick and- “Open your eyes, princess.”
Shoto does, and immediately focuses on where Izuku is wet and open for him—lips swollen and dripping onto the couch cushions, and…
Katsuki is playing with his dick, nudging the head up and down Izuku’s lips and Shoto can feel it—hot and wet and just out of reach-
He wants to rut into Izuku, fill him up, claim him, but Katsuki keeps teasing, and- Shoto swallows hard when he feels the press of something big and hard against his ass.
“You want it?” Katuski breathes into Shoto’s ear, and he shudders as Katuski starts up a slow, filthy grind. “Yeah? You want me to pound your sweet little ass into next week? Want me to fuck you full and stupid until you’re crying?”
“Please,” Shoto croaks out, feeling like he’s too hot and too cold all at once. “Please, fuck me—please, I want it, want your cock so back—Katsuki, please, fill me up, let me take it, I wanna take it, fuck me.”
“Goddamn,” Katuski swears, and Shoto doesn’t have time to think before his head is being tilted, his lips claimed in an open-mouthed kiss that’s more tongue and spit than anything. “How long you been gagging for it, princess?”
“High school,” Shoto ruts his hips, trying to find friction—plunging into Izuku’s weeping cunt, get Katsuki to fuck him, it doesn’t matter, he just wants- he wants- “Please, since high school, let me have your cock, I’ll be so good for it.”
“Fuck,” Katsuki swears against his lips, then his hands tightens around Shoto’s cock, the head pressing against Izuku’s opening and Izuku moans, long and loud as he drops his head back. “You want it, too, ‘zuku?”
“Please,” Izuku begs, canting his hips up and- Shoto’s head pops inside, presses through that tight ring and he collapses forward onto his forearms, rutting mindlessly deeper into Izuku. “Oh- Oh!”
Then Izuku goes still, back arching off the bed as his nails scrabble down Shoto’s back, and he tightens—he’s impossible tight and wet around Shoto and he has to think about Endeavor’s flaming face to keep himself from spilling into Izuku’s cunt far too early.
“Big,” Izuku gasps against Shoto’s cheek, coming down from his orgasm. “You’re so big, so long, so full, nngh-”
Shoto tilts his head to the side, and it doesn’t take any work at all to drag Izuku’s lips into a kiss. Izuku is uncoordinated, the kiss wet and sloppy and Shoto drags his lips down Izuku’s neck, biting just to feel the way he clenches around Shoto’s dick.
Izuku moans, and Shoto feels hot fingers drag his pants down—he moves so Katsuki can drag them off all the way, but he doesn’t. The blond leaves them at mid-thigh, trapping Shoto’s legs against each other.
Hot puffs of breath ghost across Shoto’s exposed ass and he shivers, even as he ducks his head down to lick across one of Izuku’s nipples, lazily canting his hips deeper into the greenette.
“You have no idea,” Katsuki rasps, “how long I’ve thought about eating this ass.”
That’s all the warning Shoto gets before a tongue, hot and thick, is laving a wet stripe all the way up his ass. Shoto bites down, maybe a little too hard, and he lets go, but-
Izuku whines, writhing under Shoto. “Please, please, more, I want-”
“Needy little slut,” Katsuki spits, pulling his face out of Shoto’s ass before pressing hand to Shoto’s lower back—all the warning he gets before he’s shoved down, forced deeper into Izuku who screams again, back arching.
Shoto groans. “Zuku.”
“Oh, you like that?” Shoto can practically hear Katsuki’s wicked little smirk as a fingertip circles around Shoto’s asshole. “You like being forced into the nerd’s sloppy little cunt? You know how much he likes being filled? Being pinned down and fucked?”
Shoto moans, dropping his head back into the crook of Izuku’s shoulder. “I can’t- Zuku, so tight.”
“Yeah, baby?” Izuku slurs. “You want it tight?”
Then he clenches, and Shoto fucks into him helplessly—at the same time that Katsuki’s first finger worms into his ass. His fingers are thick, thicker than Shoto’s, and they curl just right-
Shoto whines, trying not to come on the spot as Katuski’s fingers send bolts of pleasure through his body.
Katuski goes too fast, one finger becoming two, but the burn-
“He liked that,” Izuku wriggles contentedly on Shoto’s cock, and Shoto clamps his hands around the smaller boy’s petite waist. If he keeps moving around like that, Shoto’s going to come, and he fully believes Katsuki will follow through on his threat to fuck him into oblivion.
“Fuck, you look so pretty like this, princess.” A hot, possessive hand trails down Shoto’s back as the two fingers inside of him scissor apart, then become three. “All flushed and open for us. Tell me, would you let anyone see you like this? Anyone fuck this greedy little hole of yours?”
Shoto whimpers, shaking his head as he tries to steady his legs against the waves of pleasure that leave him shaking, tries to think about anything other than Izuku’s hot cunt around him and Katsuki’s fingers fucking his ass. “No- No, just you- just oh.”
Katsuki seems to like that, because his digs his fingers cruelly into Shoto’s prostrate, and Izuku moans drunkenly as Shoto twitches in his hole.
“You’re so long,” Izuku murmurs, tracing his fingers up and down Shoto’s side. “So deep inside of me, so good.”
“Fuck, I’m not waiting any longer.” Katsuki’s fingers withdraw, then there’s something pressing against his entrance—something big and hot and-
“Oh- Oh,” Shoto cries, burying his face deeper into Izuku’s neck as Katsuki’s head pops in. He’s big. So much bigger than Shoto thought, thick, carving his way into Shoto’s guts inch by inch. “Oh, oh, oh, oh, oh,” Shoto chants, dick-drunk and hazy—he’s going to come just from being stretched open, just from being speared on the blonde’s monster cock. “Oh.”
“Fuck,” Katsuki grunts when he’s fully seated. “So fucking tight, baby, so good for me.”
“Please,” Shoto begs mindlessly. “Please, I want it, fuck me, fuck me good, please-”
Shoto’s words cut off as Katsuki draws his hips back before slamming in.
Shoto’s eyes roll back into his head as he’s fucked further into Izuku, the boy squirming and moaning under him, babbling nonsense and praise as Shoto drools into his neck.
“You take it so good,” Katsuki pants. “Such a good little slut for us. You going to be good for Zuku? Show him what that pretty cock of yours can do?”
Shoto barely has to think before he’s rutting forward—then pulling back, impaling himself further onto Katsuki’s thick cock as he moans uncontrollably, seesawing back and forth wildly.
“So good,” Katsuki continues to spew filth, “tight little body like yours is born to take dick, isn’t it? Bet you’ll look so pretty spread open on my cock while Zuku sits on your face. Or maybe I’ll choke you on my cock while he takes you down that open throat of his.”
Yes, yes, yes, Shoto just moans in response, rutting back harder.
Katsuki groans, hands falling onto the slimmer boy’s hips as he fucks into him. “So good for me, baby. So good.”
Shoto moans at the praise—pleasure is sparking electric through his veins, he just needs, he just needs-
Izuku moans in his ear. “Please,” he begs. “Fill me up, please, I want to be dripping with you- Want to- nngh, want you to fucking breed me-”
Shoto slams home into Izuku, the words the final straw as pleasure rips through him, bright and blinding—and Katsuki doesn’t stop, sending shocks of overstimulation through Shoto as he collapses onto Izuku, painting the walls of the smaller boy’s cunt with his seed.
Something about it must trigger Izuku, because before Shoto can even reach down and play with his clit, he’s coming, screaming as he twists on Shoto’s twitching dick, squeezing out a few more pathetic squirts of cum.
Tears track down Shoto’s face as Katsuki continues to hammer into him, murmuring something about him being such a good boy and so tight for him and-
Katsuki goes rigid, a groan like sin dripping off his lips as he thrusts once, twice, then Shoto feels him twitching, shooting his cum up Shoto’s ass.
Shoto moans.
“Mmm, like that?” Katsuki slurs, not even an orgasm enough to shut up his filth mouth. “Little cumslut.”
“Fucking-” Shoto moans as another hot pulse of cum paints his inside. “Dirty talker.”
“You loved it,” Katsuki bats back, slapping Shoto’s ass lightly and sending another pulse of broken arousal through his system. “Oh, fuck, you got tight. Kinky little fucker, aren’t you?”
“You,” Shoto pants, trying to come down from his high even as Katsuki continues to twitch and pour cum into him. How much is there? “You started this.”
“Blame the nerd,” Katsuki groans, thrusting his hips shallowly into Shoto. “Fuck, you take it so good.”
Shoto swallows, trying to think around the haze of pleasure, the hot wetness he can feel inside his asshole. “Izuku?”
The green-haired boy just whimpers.
Panic flares through Shoto’s system as he struggles back up onto his forearms. What if he hurt him? What if-
Izuku’s green eyes are hazed pleasure-drunk when Shoto meets them. “So good,” he moans contently, wiggling further down onto Shoto’s dick. He almost chokes. “Wanna stay here forever.”
“Slut likes being filled,” Katsuki says fondly, grinding deep into Shoto with a final groan. “Fuck, okay, I think I’m done. You wanna cockwarm him while I go get his plug?”
“His- His plug?”
“So the cum doesn’t escape,” Katsuki says, like it’s the most natural thing in the world as he pulls out of Shoto’s ass- and Shoto’s face burns as he feels Katsuki’s mess start to drip down his thigh. “What, you want one too?”
“Maybe,” Shoto concedes, face burning.
When Katsuki comes back, he comes back to find the two of them kissing, now sitting up on the couch. Shoto’s cock is beginning to harden again in Izuku’s pussy, Izuku’s fingers jammed into Shoto’s stretched asshole to keep Katsuki’s load from escaping.
Katsuki grins at the sight, setting the plugs he gathered down on the table.
Now this, he can get behind.