Chapter Text
Being quirkless was such a huge part of who he was, it was the root of all his suffering so when faced with the option of being gifted a quirk from the number one hero in Japan one would think the answer would be simple. Izuku wasn’t just some stupid hero fanboy though; he was the one of the best information brokers in Musutafu, known as Jade Rabbit. He knew all about All Might’s quirk One for All and the powerful enemy any holder of said quirk makes, the brother quirk All for One and the fact that any holder of One for All is an instant target for the number one villain in Japan. Izuku was not stupid enough to paint a target on his back. Being friends with the villains protégé gave him more than enough intel to know that even the top 10 heroes together couldn’t bring down All for One. Shigaraki Tomura, said protégé, was pretty powerful on his own and his League of Villains with work could become a force to be reckoned with. Luckily Shigaraki was somewhat protective of Izuku viewing him as a little brother or a prized pet depending on his mood, meaning he made sure Izuku was trained to come out on top of most fights but had no interest in him joining the League or actively looking for said fights. Izuku appreciated all Shigaraki had done for him, the man literally got him to step away from the ledge he found himself on at only 10, which is why Izuku offered up this priceless information about All Might expecting nothing but continued protection and maybe help landing a place to live since his mother had informed him that once he is done with middle school he will be old enough to care for himself and she will no longer allow him to live with her. He had plenty of money saved up from his lucrative quirk analysis and information sales, but no one is going to allow a 14- or 15-year-old to sign a lease and the authorities would be called, and he really didn’t want to deal with that.
Since Izuku used to be a hero fanboy, particularly an All Might fan, he felt compelled after the slime villain incident to ask the hero a question that had plagued him when he was younger. He wanted to know if the hero thought a quirkless person could be a hero. Izuku no longer worshipped heroes like he did when he was younger, no hero stepped him to protect him from being tortured at school or neglected by his mother. It wasn’t a hero that saw him about to jump and stopped to ask him why, sure Shigaraki was just bored and would’ve let Izuku jump if he hadn’t been interested by his story and the analysis notebook Izuku had left his suicide note in, Shigaraki absentmindedly leafing through as Izuku stuttered through his sad history marked the start of their strange relationship, but the point remained a villain saved him when everyone else looked away. Izuku still planned on attending the prestigious hero school UA but that was mostly because even outside of the hero course it was still the top ranked school in that part of Japan, he was also a petty little shit and wanted to prove everyone wrong something Shigaraki found equally amusing and exasperating. Having his once hero so carelessly crush what he presented as his dream pissed Izuku off, and the casual way he explained his situation seeing no fault in outlining his weakness to a teenager he just met rubbed Izuku the wrong way. Stupid people always did get on his nerves, and he spent too much time around Shigaraki to be considerate, he picked up too many bad habits from the man something that pleased the older teen to no end.
So after instinctively saving Kaachan and being offered a chance to inherit All Might’s power Izuku rushed into a hidden alcove, calling Kurogiri and politely requesting to be teleported to the bar. Shigaraki had already been tense since Izuku was a few hours later than usual and him appearing dirty and disheveled led to an immediate inquisition. The fact that Izuku had been ambushed and saved by the ‘blond buffoon’ was enough to have Shigaraki frothing at the mouth, which only got worse as Izuku continued. Explaining that he not only jumped into a fight but also saved his number one tormenter had Shigaraki disintegrating everything in sight and tearing at his neck, the sight of the bloody marks being dragged into his big brother’s neck had Izuku once again acting on instinct wrapping his arms around Shigaraki’s slim waist pleading with him to calm down and hear the best part. He even used one of the man’s few weaknesses against him, clawing hands immediately freezing as soon and Izuku cried out for his ‘nii-san’ to stop. After telling him all the information All Might had given him as well as the offer to get trained to inherit the mans quirk led him to where he was now, in Shigaraki’s Sensei’s lab staring at the imposing and mutilated form of All for One leaning against Shigaraki and hoping his trembling wouldn’t be called out.
“I had already toyed with the idea of gifting you a quirk, especially if you managed to get into UA. Your loyalty to Tomura and the benefits from having you around are something to be rewarded with. I even know the perfect quirk ready to gift to you, something that would explain the late presentation and wouldn’t tear apart your body like the quirk All Might would give you.” Izuku jerked upright ignoring the bomb Sensei dropped about already considering gifting Izuku a quirk and instead focusing on the torn apart bit.
“WHAT’ Izuku winced at how high his voice came out, ‘What do you mean torn apart, if I had agreed with that idiot, he would’ve given me a quirk that could hurt me?” Pressing back against Shigaraki as All for One chucked, he could feel Shigaraki’s muscles tense under him a laughing Sensei usually meant trouble. They both took comfort in the press of their bodies together as they waited for Sensei to speak.
“I would hope he would at least train you a bit, but you just aren’t built to take his quirk like that, most people grow with their quirks after all. You are built rather delicately, much like Tomura you are built for speed and flexibility, unlike Tomura you do not have strength to back it up. The quirk I have devised for you will allow you to take strength from others, you would just need an offering. In a way its like what All Might would do but without the risk. To get One for All you need to be given a piece of the quirk holders DNA, with my quirk it will not be a permanent transfer and the amount of power passed is higher the more DNA you get. I call is succubus. Do you understand?” Izuku understood what All for One was saying and the implication made him flush wanting to ignore that and instead focus on what he was told, but before he could confirm his suspicions on what this quirk could do Shigaraki beat him to it.
“A sex quirk? I didn’t think you played those types of games Sensei.” Shigaraki mumbled, stepping away from him making Izuku to look up at him, the flush on Shigaraki’s face made Izuku feel better about the heat on his own cheeks. Izuku knew Shigaraki has sex, something he learned one of the times Dabi came to the bar. The fire user intrigued Izuku and pissed Shigaraki off, Izuku was sure part of the reason Shigaraki doesn’t like the burnt man was because Izuku had admitted that he found him attractive.
“So I have sex or at least sexual contact with someone and I take their energy and their quirk ability. The more of their uhm… th-their…” Izuku petered off, hiding his flushed hands in his face, “The more DNA I get from someone the faster and stronger I get. But the effect wears off, so I will have to keep getting uh… samples or I will go back to my usual strength and speed. Since I’m going to continually be uhh… feeding there won’t be such a strain on my body. How strong will I be able to get?” He was grateful he wasn’t called out about how embarrassed he was, although Shigaraki thought about it based on the glances he was throwing his way.
“You are quite right Izuku, the more samples as you put it, you get the stronger you will be. Each time you feed you will also heal. How strong or fast you become I am not 100% sure but I believe you could get to around where All Might is at. Maybe not his peak but around where he is now. I made this quirk out of a few different ones so it may have some side effects but nothing like what One for All would give you. You would turn your bones to dust trying to harness that much power all at once. Do you accept? This is a... as you say, no strings attached deal just a thank you for your companionship towards Tomura and for giving me such wonderful news.” With half of his face missing, it was hard to tell what mood Sensei was in but he sounded amused, most likely at the fact that both he and Shigaraki where still visibly embarrassed. Looking at Shigaraki I knew I wanted his input.
“Shiggy,’ I asked softly ‘What do you think.” Crimson eyes bore into mine, but Shigaraki didn’t need to think about an answer, he trusted his Sensei.
“’Zu you know I don’t care if you have a quirk, but you do want to get into UA. It would be a useful quirk to have although I can’t think of anyone I would be comfortable from you… feeding from. Will Izuku’s partners feel the… drain he puts on them?” Shigaraki directed the last part toward his Sensei, wrapping an arm around me as I tried to stop the silent tears from falling in the face of Shigarki’s warm words. I should have known Shigaraki wouldn’t care if I had a quirk or not.
“They may find themselves a bit more tired and hungry than usual, I would recommend not going to the same person multiple times in a row, but it shouldn’t be detrimental to their health it may just knock them out.” All for Ones bland response seemed to both upset and reassure Shigaraki as his grip tightened. Izuku whined in response, looking up at Shigaraki’s troubled face.
“I can’t help but dislike the idea of my darling little brother having to sleep with a bunch of different men, but a sex related quirk is the best way to explain his late development. I think it’s a good idea ‘Zu. And its not like you must always be powered up; you can continue on like this and just use it for emergencies although you really should train with it first.” Shigaraki trailed off as Izuku buried his face in his chest, embarrassed at the thought of having sex although deep down he knew exactly who he wanted to call to test out his new power once he got it.
“S-sensei… I would like t-to accept your offer. I really appreciate it.” Keeping his face buried in Shigaraki’s chest he didn’t see as the darkness the encompassed All for One stretched out, only registering the feelings of cold hands gripping his bare arms before he collapsed.