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It’s not the first time Kacchan has glitched during sex.
There’s really no other way to put it. The first time it happened, they were going at it like rabbits against the wall of the locker room when something in Katsuki’s face just changed. It startled Izuku so badly that he lost his grip on Katsuki’s ass, making him crash down to the floor, taking Izuku and his dick with him.
A humiliating visit to Recovery Girl’s office—in which she very pointedly didn’t ask about Katsuki’s purpling ass and thighs nor Izuku’s poor bent dick—later, Izuku was still unable to understand what happened, especially since he didn’t have time to think with Katsuki hollering at him like a banshee for an hour and declaring they were never having sex again.
It’s hard to explain. Katsuki’s hair had been the same color, his face the same shape, yet something had definitely been different. He just couldn’t put his finger on what it was.
Two long, long weeks later, they’re back at it with Katsuki under him on the bed, safe and secure with both his feet firmly planted atop the mattress, when that strange change happens again.
It makes Izuku jolt and jump back, a cold flush of wrongwrongwrong tearing down his spine. It looks like Kacchan, sounds like Kacchan, but something in that face is unmistakably not Kacchan.
Katsuki props himself up on his elbows, a scowl contorting his features, and that’s him, all pale hair and flushed cheeks and scarlet eyes blazing with hellfire. “What the fuck, Deku?”
“Something weird’s happening,” he stammers out before he can even think to muster any apologies.
“Yeah, I fucking got that!” He sits upright, yanking over the blanket to cover his rapidly flagging erection and the glimmering mess of lube between his thighs. Is it too late to get back to—yeah. Mood’s dead. He looks more concerned than angry. “What is it?”
“Something just… changed.”
“In my ass?”
“No!” Izuku drags a hand through his sweat-wet hair. “I don’t know how to explain it. You just looked… different.”
Rage explodes over his face. “Are you saying I don’t turn you on anymore?”
“No, Kacchan, no! Would you just listen to me? I’m saying you didn’t look like you. Like, for a second, you were still you, but a different kind of you.”
Katsuki looks like he’s struggling to understand, which turns back into anger the way a toddler breaks out into a hysterical tantrum when a toy doesn’t work. “That doesn’t make any sense. Look, if you don’t wanna fuck, just say that instead of coming up with these bullshit excuses—”
“They’re not excuses!”
“—or if it’s erectile dysfunction—”
“Erectile dysfunction?!”
“—grow some balls and admit it instead of blaming it on me being me but not really me.”
Izuku’s angry, too, now. His penis is perfectly functional, a prime specimen, beautifully shaped before he dropped Katsuki with all eight inches of it buried inside. Recovery Girl had to—never mind. He doesn’t want to remember that. “My dick works fine! You’re the one who—who changed your face!”
“Why would I change my face? How the fuck would that even work?”
They squabble until Kirishima bangs on the wall separating their rooms and yells, “Some of us are trying to sleep! If you’re gonna talk about your dicks, take it outside!”
Izuku goes crimson, Katsuki starts yelling, and nobody in the dorms gets any sleep that night.
Toshinori pales. “During… what?”
Midoriya’s plowing ahead at a thousand kilometers an hour, fifteen minutes into a long-winded explanation too confusing to follow except for a few key words: Glitch, Kacchan, sex. When his mentee asked for a private meeting to discuss an important issue with a shifty, fidgety demeanor, Toshinori assumed it was something to do with One For All or hero work or cedar trees or restaurant recommendations—anything except this.
“Well, ahem, you know,” Midoriya says eloquently, the color of a cherry. “We were, um, you know, and he—he just changed.”
“Young Midoriya, I’m not sure this is within my jurisdiction.”
“I’m worried it’s a quirk,” he blurts out. “Or that a villain did something to him.”
Toshinori releases a long, slow sigh. This is above his paygrade. “Has it ever happened outside of… when you weren’t being intimate?”
“No.”
“Hm. That’s interesting. Are you sure you’re not just—” He tries to think of a more delicate way to phrase it, but there’s no other choice. “Getting caught up in mental fantasies?”
“I’m not fantasizing about anyone else,” he says earnestly, dismayed. “I was just looking at Kacchan, thinking of how pretty he is and how good he looks when—”
Toshinori coughs, holding up a hand. “Young Midoriya, please.”
“Sorry! I just meant I was never thinking about anyone except him.”
That’s bemusing. Toshinori has heard of mistaking a lover for someone else, saying the wrong name—not that he had much experience in that department—but Midoriya seems certain that there was a literal change. Maybe he’s right in suspecting foul play or villain activity.
“Ask Recovery Girl,” he says finally. “I’m sorry, but I don’t think I can help you. This sounds highly unusual. Perhaps she could tell you if she’s heard of any quirks like this.”
Midoriya zips off, and Toshinori starts looking up products akin to mental bleach.
Recovery Girl does an admirable job at concealing amusement, judgment, and plain confusion as she checks Izuku’s eyes, his brain, and the rest of his body for lingering traces of a quirk. She suggests bringing Katsuki in for a check-up as well, but under peril of dying in a fiery explosion if Kacchan found out he mentioned their sex life to multiple pro heroes, Izuku decides that might not be the best idea.
“You’re all clean,” she says once the examination is over. “No evidence of quirks or physical damage. I can’t do anything else without examining Bakugou-kun as well.”
“Well, have you ever heard of a quirk like this?” he asks, trying not to sound frustrated. “That can make you look different? Like a different version of yourself?”
“A lot of glamour quirks have that effect, but I don’t know of any that flare up specifically during intercourse. It’s best if you chalk it up to a fluke and come back, with Bakugou-kun, if it keeps happening.”
In the interest of preserving his life, Izuku will most definitely not be doing that.
In the wake of a wasted afternoon in which he was examined and felt up all over only to receive an unsatisfying response, Izuku turns his attention to other methods of research.
After all, he’s been approaching this the wrong way, fumbling around in the dark and oversharing to pro heroes he can never look in the eye again. What he needs is a proper system of research, starting with the easiest method to gather data: Interviews.
He ambushes Uraraka when she’s digging through the cupboards in the kitchen, a steaming cup of tea and an empty saucer laid out on the countertop. “Uraraka-san, have you had sex?”
Her head snaps up, banging hard on the still-open cupboard door. “Ow!”
The reddening bump is swelling, larger by the minute as they sit in the common area with the tea and a pack of biscuits that Izuku found for her; a small form of compensation.
“Why did you ask?” she croaks out, holding a blue sparrow-shaped ice pack to her head.
“I’m having a weird problem.”
“Please don’t tell me about your penis.”
Heat flares in his cheeks. “That’s not what I meant. It’s just that the last couple of times we’ve done it, Kacchan suddenly looks different. And the thing is that he still looks the same, just… different. The first time it scared me so bad I dropped him and almost broke my—”
“Don’t say penis.”
“I wasn’t,” Izuku says. It’s a poor lie. Uraraka’s judging him. Oh, god, she’s judging him. Why did he think interviews were a more appropriate method of gathering data than online research? It’s a good thing he didn’t become a scientist. “Have you ever experienced that?”
“No,” she says decisively. “I mean, there was this one time I was with this guy—”
His eyes go wide. “Who?”
“Nobody. It’s not important.”
“You have a boyfriend?”
“It was someone from Class B, alright? We were just kissing, and he made a sound that kind of sounded like…” She clears her throat. “Someone else. So I couldn’t stop thinking about that person, and then it kind of felt like I was… you know. Do you mean like that?”
“No,” he says with an exasperated sigh. Then what she said hits him a second time and he squints suspiciously. “Who were you thinking about?”
Her cheeks turn the color of the pink-frosted biscuits on the plate. “No one! Why’re you so nosy today?”
“I told you about my sex with Kacchan,” he protests, and she makes a sound like she was punched in the throat with a frog. “Don’t friends talk about that stuff? I always hear Kaminari and Mineta talking about it—though, to be fair, neither of them get any.”
That manages to make her snort. “Yeah, exactly. We don’t talk about the sex we’re having.”
“But I’m not having any! Kacchan says he’s sick of me leaving him with blue balls and—”
She drops her head into her hands with a thunk. “This is happening. You’re telling me about Bakugou-kun’s balls.”
“I’m not talking about his balls! Well, kind of, but only in a metaphorical sense. His real ones aren’t blue, that would be very concerning—they’re actually a nice color, kind of pink—”
“Deku-kun!”
“That wasn’t my point,” he emphasizes, frustrated. “I just meant that he doesn’t want to make love anymore because I almost broke his pelvis, which is justified, I guess, except I told him it’s safe if we’re on the bed, then I freaked out and jumped off him again which just made him madder, and it’s happened a few times after that and I’m at the end of my tether!”
It takes a few seconds before the shame, guilt, and abject horror sets in.
Yeah. Maybe he got carried away.
Uraraka draws a deep inhale that keeps going for a long time, then huffs it out all at once. “I’m sorry you’re… sex-less, but this sounds like something you need to work out with Bakugou-kun. Now, if you’ll excuse me, I’ll be finishing my tea then avoiding you for several weeks.”
He gulps. “Fair enough.”
Then it gets weirder.
Izuku’s lying on his back with Katsuki stretched out on top of him, his face tucked into Izuku’s neck, sighing contentedly into his skin as Izuku strokes his back. There’s no funny business going on at all, both of them fully clothed with at least four layers separating them—just slow, tender petting and breathing into the peaceful silence of the dorm room.
A sharp pang strikes Izuku’s stomach, and he lets out a choked noise, clenching up as a wave of emotion crashes over him like an ice bucket perched on top of a door. He’s always been emotional when it comes to cuddling Kacchan, but this—this is like multiplying it by three and slamming a truck loaded with it into his ribs.
Katsuki looks up, eyebrows furrowed with worry. “What? What’s wrong?”
“Nothing,” he squeaks, patting Katsuki’s lower back as if soothing a baby. “Put your head down.”
“No. Tell me what happened.”
“I just felt this… want.”
His expression goes bemused. “You made that ‘can’t breathe’ noise because you’re horny?”
“No! It was more like the times before we were dating when I’d look at you and wish you were mine so badly that it felt like I would die if it didn’t happen.”
“But I’m right here.”
“I know.”
Katsuki takes his hands off Izuku’s shoulders, leaving them cold, and pushes himself upright, sitting back on Izuku’s stomach in a way that would be hot if he weren’t terribly confused right now. “You’ve been weird lately. First you freak out when we’re banging, now this—even All Might’s been avoiding me. What’s going on?”
“I don’t know,” he bemoans, chest heaving harder under the exertion of breathing with a Kacchan sitting on his stomach. “If I knew, I would tell you, but I swear I don’t get it. All I know is that you look different sometimes, and now I feel like you’re out of my reach even though you’re right here. I want you so bad, Kacchan—this is really confusing, but the one thing I’ve never doubted is that I want you just as much as I always have.”
He huffs, his expression softening. “Shitty nerd. You need to stop overthinking things. Just… close your eyes. Stop looking at me until this weird thing goes away.”
“But I love your face.”
“You can love my face with your eyes closed.”
A smile tugs at his lips. “Oh, like this?”
Shutting his eyes, he pulls Katsuki down onto him and starts pressing messy kisses all over his face; his eyebrows, his nose, the soft, warm place where his eyelids meet the bridge of his nose. He hears a laugh, Katsuki wriggling in his arms like he’s trying to get away, and Izuku just smiles as he rolls onto a laughing, squirming Katsuki and continues kissing his face and neck, warmth seeping through him like spring sunshine.
The next time it happens, Katsuki’s hair changes color.
He’s fucking Katsuki from behind, one hand on the back of his neck, pushing his face into the pillow. It took a while to convince Katsuki to have sex ever since the recent happenings, but he’s clearly enjoying himself now, moaning and shoving his hips back, demanding more.
Then Katsuki’s hair goes orange.
He’s so shocked he stops, and Katsuki makes an impatient noise, wriggling his hips. “Keep going.”
He blinks, and Katsuki’s hair is back to blond. On the next blink, it’s orange again.
“Your hair’s orange,” he says dumbly. With all the changes that happened before, it had never been this obvious—plain as day, spiky orange strands in front of him like a cactus flower.
“I don’t care,” he groans, “we’ll talk about it later, just fuck me!”
Still stunned, Izuku keeps going, though his pace is less certain than it was before. Katsuki seems satisfied, but he can’t enjoy this to the fullest when he’s reeling under the fact that Katsuki’s hair had changed to a blaring, obvious, unmistakable shade of orange, even if it was back to his usual dusty blond now.
Afterwards, when Katsuki’s lying sticky and sweaty on his chest, he repeats, “Your hair was orange.”
“Maybe you’re going crazy,” he says sleepily, snuggling into the crook of Izuku’s neck. “Now shut up and let me sleep.”
He looks at Katsuki’s hair, but it’s blond as ever. Maybe he really is losing his mind.
It all falls into place a few days later.
He’s having a good dream. He’s in a bed of clouds, and delicious pressure is rubbing over his boxers, coaxing deep, satisfying waves of pleasure from him. He can feel the dream slipping away as he eases into wakefulness, but the pressure is still there.
Blearily, he blinks his eyes open to find Katsuki lying on his side beside him, his hand moving between Izuku’s legs. So, not a dream. It’s rare that Katsuki wakes him up this way; usually, it’s only for special occasions or if he’s done something very, very good.
“Kacchan,” he murmurs happily, leaning over to press a kiss to the peak of Katsuki’s cheekbone. “What’s this for?”
“Just had a good dream.”
“Mm, what was it about?”
“Not important.”
His eyes drift shut as Katsuki’s hand slips under the dampened fabric of his boxers, relaxing into the bed. “Well, was I in it?”
“…Not exactly.”
Immediately, his eyes fly open.
He shoots upright, the motion jostling Katsuki’s hand out of his boxers, shooting him a betrayed look. “You had a sex dream about someone else? How could you?”
“It was a dream,” Katsuki fires back. “I don’t control what my subconscious comes up with! And what about the time you dreamt you fucked IcyHot, huh?”
“I never—”
“I saw that wet patch in your underwear, and you couldn’t look him in the eyes the next day! I’m not stupid. Dreams are just dreams.”
He sighs, feeling embarrassed. “Okay, you’re right. I’m sorry.” He places his hand on Katsuki’s chest, fingers brushing against his collarbone. “Why don’t you tell me what happened? Maybe I can make it happen for you.”
“Okay,” he agrees, looking relieved. “There was this guy—”
“Who?”
“I don’t know. It was some dude I’ve never seen. He looked pretty familiar, though—white hair and eyes kind of like yours. He was fucking me, and I wanted him to go faster but he kept going so slow and—”
A weird feeling was forming in Izuku’s gut. “What did he look like?”
“I told you, he had longish white hair with bangs and green eyes. Pretty skinny, maybe a bit taller than me—”
“Kacchan.” The feeling had solidified into cold, hard realization. “Do you remember anything about the vestiges from when you and I shared One For All?”
“No, I—” His eyes widened. “If you’re about to tell me that was—”
“I can’t believe you cheated on me with the first One For All user!”
“What?”
Izuku felt an odd urge to scrape into his head and give the first user a piece of his mind. “What does he have that I don’t?”
“First of all, he’s dead,” Katsuki shoots, “and it was just a dream!”
“I’m talking to him about this.”
“Wait, Deku, wait—”
Izuku stumbles out of the bed and towards the closet, slamming the door behind him. He can hear Katsuki outside, but after a few seconds, there’s a loud huff and another door slams shut. He can apologize to Katsuki later. For now, he needs to fall into his subconscious and have a serious conversation with the man who had the nerve to dream-fuck his Kacchan.
The vestige world is cool and calm. Grey walls line the surroundings but never seem to draw closer or further no matter where he moves, circling around the seats that have now become familiar to him. A haven of peace and quiet for those who grapped with One For All before him and lost their lives trying to stop the worst villain that society had ever seen.
Izuku storms towards Yoichi, who’s standing with a calm, resigned expression beside his throne. “You. You had sex with my boyfriend.”
”Why’d you have sex with his boyfriend, Yoichi?” Bruce teases. At a meaningful look from Nana, he falls silent, though it’s hard not to notice him practically vibrating with glee.
“It was his subconscious,” Yoichi says, far more gently than Izuku can admit he deserves. “And like he said, it was just a dream.”
Izuku wants to accept the answer, but a dark, petty part of him can’t get over the fact that his boyfriend had enthusiastic dream-sex with All For One’s brother. Maybe it’s the sexual frustration. Maybe it’s the fact that no one has given him anything resembling an answer to all his questions about the changes he’s been seeing and feeling.
Or maybe it’s that when his gaze drifts to the side and lands on Kudou, realization crashes down onto him like the sun dropping out of the sky.
“It’s you.” Izuku stares at Kudou, his jaw ajar. “It’s you I’ve been seeing.”
There’s a loud, telling silence.
Kudou gives a heavy sigh. “Okay. You’re right.”
“But… why?”
There’s another long silence, then Bruce speaks up. “You might as well tell him, Yoichi. The kid’s earned it.”
Yoichi’s face has gone a soft shade of blush. “Well, alright. It has been brought to my attention that my… feelings may be influencing other holders of One For All.”
Izuku’s still reeling. “What’s that supposed to mean?”
“It means,” Shinomori says firmly, “that all of us have had this problem. Whenever we have sex with someone, they start to look like Kudou. It’s worse for you because your boy actually looks a lot like him.”
Izuku’s mouth falls open. “All of you?”
“That’s right,” En says with a very blatant side glance at Yoichi, making him bow his head in shame. “Yoichi’s love for Kudou ruined all of our sex lives. I can’t tell you how many times I tried to get my rocks off only to have the girl start to glitch out and look like a certain man.”
“My husband’s hair often turned orange,” Nana chirps. “Once, we were in front of a mirror, and—” A wolf-whistle interrupts her, and she coughs, embarrassed. “Well. You know how it is. His hair changed color but he didn’t see anything. We both thought I was going insane.”
“I’m sorry,” Yoichi says, his cheeks crimson under his loose locks of hair. “Obviously it wasn’t intentional, but… there’s just so much longing that I’ve had to repress. We never…” He bites his lip, shooting a glance at Kudou, who stares back at him unapologetically—“Ever since Bruce joined us here, we haven’t been intimate, and I can’t help wanting to.”
Izuku finally finds words. “Why not?”
“Look around, Ninth,” Kudou interrupts. “We’re all here together. It isn’t exactly decent to fuck in front of an audience.”
This might be the weirdest thing that has ever happened to Izuku. The users are looking at each other with varying degrees of amusement while Yoichi looks like he wants to run away to Okinawa and fish for the rest of his days.
Izuku had come up with a thousand theories as to why Kacchan sometimes looked different, everything from accidentally ingesting poison that one time he ate pufferfish or this being a latent quirk he somehow never found out he had, but he could have never imagined this.
He was seeing his boyfriend as the second One For All user because Yoichi wanted to fuck him so badly.
Yep. A lifetime of thinking wouldn’t have been enough to come up with that one.
“You could…” he begins hesitantly. “Ask everyone to turn around?”
“No,” En jumps in. “No way. Do you really think there’s any chance we wouldn’t hear… noises?”
“Plus,” Bruce interjects, “we have access to each other’s memories. Leader is loud.”
“Oi!” Kudou shoots him a fiery glare. “Shut up. We agreed not to look into each other’s heads.”
“We can’t help it. It gets boring, and you have a lot of juicy stuff in there.”
“I’m sorry,” Yoichi says again, giving Izuku that sad, solemn look not unlike a kitten begging for treats. “Bakugou-kun just looks so much like my Kudou, and seeing the love you have for each other… it reminds me of what we shared. Even holding each other feels indecent in front of our friends, not to mention that it’s a violation to do that within you without your knowledge. Looking at Bakugou-kun makes me feel like I’m with him again.”
A pang twinges at his heart. It’s sad and beautiful and disturbing all at once.
“But he’s my Kacchan,” is all Izuku can manage to say.
“Kudou was mine before you were even born,” says Yoichi in an uncharacteristically confrontational tone. “Though I do have to say that Bakugou-kun’s dream really was nothing to do with me.”
All eyes swivel to Kudou.
“Don’t look at me,” he says sullenly, crossing his arms. “I didn’t ask Yoichi to stroll into the Tenth’s head and dream-cheat on me.”
“But did you influence his dreams with your own pining?” En says, clearly enjoying this, while Yoichi gives Kudou a reproachful look at the phrase dream-cheat. “You heard what Yoichi said. Maybe you miss sex so bad it’s leaking into the kid’s subconscious.”
Kudou stomps over to the wall, facing it without another word while En laughs, satisfied.
“Why didn’t All Might tell me about this?” Izuku asks, feeling weirdly betrayed. He’d opened up to All Might only to be sent on a wild goose chase around Recovery Girl and his classmates.
Shinomori snorts. “He didn’t exactly get a lot of action. The few people he was into looked and acted differently enough from Kudou that they didn’t capture our picky Yoichi’s attention.”
Yoichi shoots him a look, but doesn’t dispute it.
“I once told Toshinori that One For All is romantic,” Nana says with a wistful smile. “The truth is that even if it was unconscious, almost all of us have gravitated towards someone like Kudou one way or the other. Like Shinomori said—it’s more intense for you because you fell in love before you even got this power.” She laughs. “You’ve always been the most like Yoichi out of any of us.”
Izuku can’t help but smile. He thinks of Kacchan, and how he would feel if they were torn apart only to be reunited somewhere they could live on together, and he can’t fault Yoichi.
“It’s more pervy than romantic,” Bruce jokes.
Yoichi just smiles, looking over at Kudou. “No, it’s love.” Kudou smiles back at him, even as the other vestiges pretend to gag.
“You just have to get used to it,” Nana tells him, placing a comforting hand on Izuku’s shoulder. “It’ll pass. Just remind yourself who you’re with and you’ll be fine.”
“Or keep your eyes closed,” Banjo supplies.
Izuku sighs. He loves looking at Kacchan too much not to keep doing it, but reminding himself it’s Bakugou Katsuki he’s with and not whatever image he’s seeing… that he can do. “Alright.”
“Ah, Izuku, harder!”
“I’m trying!”
“Not trying hard enough! Put your quirk into it, come on, pound me, what’re you waiting for?”
With a huff, Izuku thrusts into him harder, making him groan and arch his back, heels digging painfully into the small of Izuku’s back, which’ll definitely bruise tomorrow. It’s worth it to see that pleasure-drunk blush on Katsuki’s face, hear those loud, obscene noises that keep falling from his lips no matter how many times their friends complain that Saturday night makes this floor of the dormitories sound like a hentai.
He’s losing himself in the feeling, drinking in every little twitch and scrunch in Katsuki’s face when it changes—locks darkening into orange, the curve of his jaw hardened, more mature.
Izuku grits his teeth and keeps rolling his hips, trying to ignore the weird discomfort in his chest. This is Kacchan. He’s fucking his childhood friend Katsuki, Bakugou Katsuki, his lover and best friend and the boy he knows he’s going to marry someday.
He raises his gaze back to Katsuki’s face, and he’s balls-deep inside Kudou, Second One For All user, Shigaraki Yoichi’s lover.
He screws his eyes shut, cursing the day he received OFA.
“Izuku? You—” Katsuki pauses, his voice taking on a knowing tone. After Izuku explained the truth to him, he’d melted down about Izuku seeing a different man while they were fucking before the sheer hilarity of the situation sunk in and he proceeded to tease a sulky Izuku for the rest of the week. “Is it happening again?”
“Yeah,” he says miserably.
He gives a wicked grin, wrapping his arms around Izuku and letting out an exaggerated, drawn-out moan. “Oh, Yoichi, keep fucking me like that.”
“Kacchan.”
“What? He gave you One For All. Let him have this.”
“Fine, Kudou,” he fires back at him.
A soft, familiar voice fills the inside of his head. I suppose I deserve this.
There’s a holler right after it. Get revenge for us, Midoriya! We’ve all suffered so much.
It’s one of the weirdest things Izuku has done, fucking his boyfriend while they moan the names of strangers into each other’s mouths between giggles and playful shoves, but Katsuki’s shaking his head and smiling up at him with sparkling eyes so he’s more than okay with it.
Kirishima’s voice comes through the wall, loud and bewildered. “What are you guys doing?”
They meet each other’s eyes, then break down into laughter.