5

Izuku Midoriya can't do this.

He just can't.

He's accomplished a lot in the past couple of years of his life. He's excelling at school, volunteered at summer camps for kids, he's started an intramural soccer team which he co-captains with his buddy Iida Tenya, he's been a doting boyfriend, a good son. Izuku Midoriya has grown into the kind of guy that his teenage self would be both surprised by and proud of. Izuku Midoriya hasn't backed away from a challenge in years. As much as he hates to admit it, Kacchan was partially responsible for that. Something about being with Kacchan gave him… incredible confidence. Made him more daring. All of a sudden, there was this drive that ignited in Izuku's heart; Kacchan was so amazing and he made him want to be better. Once he had that spark, Izuku was pleasantly surprised to find out that he's actually… good at stuff. A lot of stuff.

But this? This might be the final straw.  

Kacchan is his step-brother. Izuku lets out an insane laugh. His step-brother. The guy he lost his virginity to, the guy who he still imagines when he masturbates, the guy he's still in love with after three years of not seeing each other, is his step brother.

Did he say in love? He meant attracted to. Because Izuku is a smart man with a girlfriend, he doesn't 'love' former sexual partners that disappeared for three years without a word! That are his step-brother now!!!! But damn, Izuku is definitely attracted to him. Kacchan is this big, beautiful celestial body and Izuku? Well, Izuku is a comet rapidly careening towards his own demise.

Here's the thing. Because of stupid Kacchan and his stupid bad temper and shitty attitude, Izuku may or may not have developed some… peculiar likes.  Don't get him wrong, he's actually quite tame, all things considered. He's in college, specifically an engineering college filled with nerds like him, and people having sex in general is sort of a novelty. Actually, he's probably the most 'adventurous' and even 'experienced' one in his entire friend group.

Which make what he wants a little… difficult to obtain. Truthfully, not a lot of people are comfortable with the whole 'pushing him around, threatening him, treating him like garbage' gambit. Not for lack of trying, though. Ochaco has definitely tried. But every time she'd try to call him a 'bitch' she'd burst out in giggles, which was definitely adorable, but not at all sexy. No one is able to dirty talk like Kacchan – he always balanced that fine line between hot and threatening, and Izuku walked the tightrope whenever the fuck he could!

There was theoretically one way of bridging that. If he wanted to feel kind of threatened and pushed around, he could be… sleeping with dudes. But, honestly? Since Kacchan, he hasn't… been able to… hasn't wanted to… Shit. Fine. Hasn't had any desire to get fucked by any man that isn't him. Whatever, its embarrassing and cheesy and sentimental. It wasn't for lack of trying. In his first couple of months of college, Izuku tried to replace Katsuki. He really, really did. Not all engineering dudes are butt ugly, and some of them are even 'gay' or 'bi' or 'bored' or whatever. He's sucked a cock or two. Or four. But when it came to the main dish? He just… couldn't.

So he decided he didn't like men anymore. It's a classic A=B, B=C, A=C scenario. Izuku hasn't wanted to have sex with men. Not wanting to have sex with men is straight. Izuku is straight! The thing with Kacchan was just experimentation for a young, inexperienced boy! Now that he's an adult who has sexual options galore, he has no reason to be attracted to anyone with a dick!

Kacchan dropped right back into Izuku's life, and look at that. All of a sudden, Izuku's ready for a cock-buffet. Eggs beneDICK for breakfast, cuCUMber salad for lunch, shrimp COCKtail for dinner. And Izuku hasn't even moved on to the phallic shaped foods yet!

Izuku's got a serious problem. Izuku always (jokingly) thought that he'd stand in line to lick the sweat off Masaru Bakugou's balls just to know what Katsuki's might taste like, but he's tilting dangerously close to actually asking. Gross. Izuku's so gross. Especially 'cause his mom's already been there. Urgh. Oh no. Why the fuck did he even think about that?! He wants to dissolve himself in acid.

Izuku is just a man! And he is freaking the fuck out.

Who is he supposed to talk to about this?? Who in the world would understand and not judge him? Asui is closer friends with Ochaco than she is with him, Iida is kind of tight lipped about stuff like that so not him, Ochaco is… well, he sure isn't going to talk to her, and that leaves?

Mr. Reasonable. Why did it have to be Mr. Reasonable?

Izuku paces the room, worrying his lip.

"I don't see what the problem is," Todoroki Shoto's voice rings out in Izuku's ear, and he frowns.

"Really? You don't see the problem with this situation at all?"

"You're not related. You had a relationship before your parents did. It was consensual, and then it ended. You're both capable of being mature adults about this."

"Yeah, but it wasn't over!" Izuku hisses, and immediately regrets it. Wasn't it, though? It definitely is now.

"…It sounds more like you don't want it to be."

Izuku sits down on his bed and stares at Kacchan's empty side of the room. Its exactly the same as it was in high school. Plain black sheets, no posters, neat and tidy. It shouldn't be making his heart do these stupid acrobatic flips in his chest, but it does.

"…I don't think I should be alone with him. I don't trust myself. He's got this… power over me. I can't even explain it. Every time he's around, its like he's pulling me into his gravitational field…"

Todoroki hums thoughtfully on the other line. "Like a black hole."

God, what Izuku would do to actually go inside his black hole…

Izuku shakes his head. He's about one stupid thought away from smacking himself in the face. Todoroki is right! He's an adult! He's capable of being mature!

"Then don't be alone with him. Its just two months. Attraction and lust are normal emotions, and they pass. You've been friends with Ochaco for years – no matter how black hole-y this 'Kacchan' is, I know you wouldn't do something that might hurt her."

Urgh. Todoroki is right. He's always right. Izuku isn't going to ruin things with Ochaco just because he can't keep it in his pants. He can be responsible and mature about things. He just needs to make it through the next two months, and it will be like none of this disaster ever happened. This is… this is exposure therapy! The more he sees Kacchan, the less he will react to it. Yes. Yes, that makes complete sense!

With a renewed sense of vigor and relief, Izuku calls his girlfriend.

"Hey Deku! Whats going on? Did you finish moving in?"

Izuku looks around at the mostly empty bedroom, save for his bed and work-desk, precariously pushed up against the wall to allow for more room for Kacchan's stuff. He swallows dryly, watching Kacchan's bed like its about to come alive and eat him. Just across from it is Kacchan's closet, which has Kacchan's clothes. Kacchan's clothes, that smell like him. And in the bathroom, is Kacchan's deodorant, Kacchan's shampoo. Izuku exhales shakily, rubbing his eyes hard. What the fuck is wrong with him?! Yeah, he definitely… definitely should not be here alone.

"Uh. Yeah. Hey, you mind if I come over, or we go out or something today?"

"Oh, sure! How about I come over and check out the new place?"

"Wha - ? Wait. No. Hold on –"

And just like that, Ochaco is over. In Katsuki's house. Because Izuku's life is ridiculous, his girlfriend is over at his former-whatever's house. Which, he supposes, is now his own house. Izuku shuts his eyes tight at that thought, face contorting as if he's eaten something sour.

Ochaco laughs and hops onto Izuku's bed, bouncing a few inches.

"Urgh, this is just like the dorms! Dude, this sucks! Where's the privacy?" she groans, starfishing on his old All-Might themed sheets.

Izuku sits down in the corner, rubbing the back of his neck, keeping a wary eye on Kacchan's side of the room.

"Yeah… but its only for two months." Izuku asserts, more to himself than to Ochaco.

She sits up and drapes herself over him, hugging around his neck.

"When are you gonna get your own place? I'm tired of running around Shoto and Tsuyu," she lands a thoughtful peck against his cheeks and he flashes her a nervous smile. "Where is your brother, by the way?"

Izuku flinches again, but attempts to avoid correcting her. Izuku doesn't need the third degree from her again. After all, it is kind of weird that he's having such a visceral reaction to it. Most people would be suspicious.

"Eh, he went off to the gym or something. I don't know."

"…So we have the house to ourselves?" Ochaco asks in a curious voice. Izuku looks at her and she raises her eyebrows suggestively. Before Izuku has the chance to protest, she jumps on top of him, trapping him in a playful kiss.

Izuku relaxes into his girlfriends lips and wraps his hands around her tiny waist. Yes, this feels right. Soft, cherry-flavored lips. Round hips, soft legs. This is what he wants. She laughs against his mouth as his fingers start to drift under her shirt, when Izuku hears the bedroom door creak open.

Izuku's eyes fly open, and he just about tosses Ochaco to the other end of the room, instead her awkwardly tumbling to the other end of his bed. He sits up, eyes wide.

 "No, no, don't stop on my account. I'll just watch."

Izuku's mouth drops. Walking through the door, nonchalant as he can be, is Kacchan. He's toweling off his wet hair, wearing nothing but low-slung sweatpants, his chest glistening with drops of water. He's… unreasonably ripped. Like. He must be photoshopped. Izuku's never seen an actual person with that abdominal V-muscle, and he's pretty sure the man's pectorals are larger than his girlfriends honest-to-god breasts.

His girlfriend, clearly not noticing Izuku's saucer-eyes, simply yelps and blushes. She wipes at the side of her lips and corners of her eyes, in a hopeless attempt to fix her running mascara. Ochaco grins and winks in Izuku's direction before she's hopping off the bed, quickly occupying the same bathroom that Kacchan just exited.

As soon as the door to the bathroom closes, Kacchan's on Izuku, practically lifting him off the bed by the neck of his shirt, expression fixed in a furious snarl.

"What the fuck did I just tell you? You incapable of listening, shitty Deku? What makes you think I want to watch you get your rocks off with some girl? Huh?"

Katsuki grabs Izuku by his hair and pulls, hard, tilting Izuku's head up so he can meet his furious eyes. Yet, the sensation of Kacchan pulling on his hair rapidly changes from pain into pleasure, and Izuku feels his breathing hitch. He licks his sensitive lips, arching his neck into the touch involuntarily. He stares back into wine-red eyes, sneering, feeling his own heart speed up to unfathomable speeds. Izuku shivers. Oh my god. His hand is so big. Jesus Christ, when did Kacchan get so fucking huge? Sure, he was buff in high school, but this is ridiculous. Their height difference isn't that crazy, but with how broad Katsuki's chest is, Izuku must be like… half his size. And Izuku is no slouch. He'd have absolutely no problem pushing Izuku down to his knees and sticking his cock down Izuku's throat – he's got half a mind to beg him. Izuku's hands start to shake. Shit. Shit, shit, shit. He's so close. He's too fucking close.

The memories spring, unhelpfully, into Izuku's mind. Izuku, helplessly following Katsuki as he stormed off, pissed about… about something. A debate in class, maybe. Izuku hardly remembers. Remembers Izuku grabbing at him in the hallway. His furious red eyes sneering in his direction, "Gargle my dick and balls, bitch." Izuku's own heated stare back. Shoving Katsuki back into the storage supply room, barricading it with a chair, throwing off Kacchan's belt like it personally offended him. The fucking scent of Kacchan's musk, the sweat. Kacchan's animalistic grin as, Izuku on his knees, he gripped into his hair and fucked into his mouth, Izuku sputtering and salivating all over this thick cock. Hollowing out his cheeks and feeling tears spring to his eyes as Kacchan bore into him, fucked his throat raw. The satisfied, dark look in his face as he pulled hard against Izuku's hair, shoving his member deep down his throat to coat his tongue in cum. Izuku would wipe his mouth, messy and spit slicked, and Katsuki would grab him by the tie, jerking him up, before mashing their mouths together. They'd grind into each other and make out for an hour, both of them missing class, high off each other, nothing else mattering but the feeling of their bodies against the others -

"We weren't – " Izuku tries to defend, voice dying in his throat, eyes clouded by something entirely different, something he's forgotten that he can feel something scared and ecstatic.

Katsuki's knee skirts up in between Izuku's legs. He doesn't stop until Izuku's erection is pressing up against Katsuki's knee.

"Then why are you so hard, you gross bitch?

Oh, Izuku is fucking in to this. Its taking everything in him not to slam their mouths together. Defiantly, he leers straight into Katsuki's red eyes, refusing so show any sign of weakness.

"You're such a piece of shit. I fucking hate your guts, you know that?" Katsuki sneers, and Izuku closes his eyes, biting into his lips, refusing to let his true reaction cross his face. He can't give Katsuki the satisfaction, showing him how he still affects him.

"You're being such a dick, Kacchan! I live here too, and if I want my girlfriend over, she's going to come over!" Izuku defends, and something dangerous and defiant springs forward to his tongue. He's unable to stop himself before the words are out, knowing full well that its going to make things a hell of a lot worse for him. "And you're gonna shut up and watch like the cuck you are!"

A vicious grin spreads across Katsuki's face and his eyebrows bristle. Izuku imagines this is what a lion looks like when it's about to break the neck of its' prey.  

"Oh ho ho. Ohhhhh you've done it now, Deku. You haven't even begun to see how much of a dick I can be.  I'm going to fucking ruin your life, you stupid cocksucking slut."

Izuku feels heat climb up his neck, settling in his ears. Jesus. What was he saying about dirty talk? Kacchan could wipe the floor with him and he'd say, yes please sir, may I have another?  

"I'd like to see you try!" Izuku spits back.

Katsuki's knee is now pressing very hard into Izuku's dick, and he's not even mad. The energy between them changes rapidly, and Katsuki quirks his eyebrows, hands digging further into Izuku's hair, only to be met with a defiant glare and a lick of the lips. Something about this feels intimate, familiar, and Izuku's about to -

"Whoa, what's going on here?" Ochaco comes back. Izuku's darts his head to look at his girlfriend, color springing front and center to his cheeks. His heart is racing – he feels like he's been caught with something, and he opens his mouth to say something.  Jesus, anything.

With a jolt, Izuku feels Katsuki forcefully push Izuku back onto his bed, letting go of his rumpled up shirt.

"Hey, are you trying to hurt Deku? I know you used to bully him, but seriously, why can't you guys get along! You're brothers!"

Izuku flinches. Oh, yeah. Thanks, Ochaco. For the reminder.

"Oh, did Deku tell you that? What other shit did your precious Deku tell you?" He's got a solid foot on the girl, and he glares down at her. She doesn't seem to care at all, crossing her arms in front of her chest and cocking her hips.

"You're not gonna intimidate me, you creep! I'm not afraid to kick your ass."

Katsuki lets out a laugh and casts Izuku a disgusted look.

"Deku's always liked them feisty, eh little brother?" With that, Katsuki grabs a shirt off his bed and walks straight out the door.

Izuku tries to catch his breath, desperately praying that his girlfriend doesn't see that he's absolutely tenting his pants, his previous uh… impotence… suddenly not an issue anymore.

"Gosh, I'm sorry Deku. I didn't know that he was still picking on you. He's so grossly alpha male. I hate guys like that." Ochaco sits down on the bed and rubs his back comfortingly. Izuku sits up and gives her a tight smile, re-adjusting his position, his erection poking into his leg stupidly.

Izuku reaches his hand out, returning his girlfriend's backrub, staring at the closed door to their bedroom.

"Nah… Kacchan's a kitten. He acts tough, but underneath it all he's a sweetheart. You'll like him once you get to know him." Izuku says flippantly.

Izuku's eyes widen. He throws his hand over his own mouth. He darts his eyes over to Ochaco, watching in horror as his very bright girlfriend connects the dots.

"….. Deku…? What did you just call him?"

"Ochaco, I can explain, its not – "

Izuku can see the gears turning in Ochaco's head. He really wishes he had some kind of stick to put into the gears and make them grind to a halt.

"…Kacchan? That sounds kind of like that nickname you give to me sometimes when we…"

Izuku flushes from head to toe.

"…You're not saying O-chan…. are you? You're – you're saying his name. Deku, what the fuck?" Ochaco hops up to her knees so she can look down on Izuku. And, man, Kacchan didn't scare him at all, but this? Izuku cowers, leaning away from Ochaco, mouth fixed in an uncomfortable grimace.  "Are you having fantasies about having sex with your step brother?!"

Izuku throws his finger to his mouth, shushing his girlfriend, which only makes her look more furious.

"Its not like that! Look, we…" Izuku considers telling her that they hooked up a couple of times. A couple of times. Ha! Hundreds of times. Izuku actually lost count around orgasm number one hundred and twenty. But he just… can't. Not with the horrified look that his girlfriend is giving him right now.

"I had a big… crush on him in high school. It was perfectly innocent!"

It was probably the definition of not perfectly innocent.

"….Wait. He calls you Deku. I've never heard anyone else call you Deku."

"I'm – "

"So that's why you like the strap? So you can pretend you're being fucked by… by that guy?! Your step brother?!"

"Ochaco… please."

"Do you still…like him?"

Does Izuku still like him?

"I don't know! I don't really… know him, anymore." Izuku says, truthfully.

Which isn't not true. He knows that he's physically attracted to Kacchan, sure, but does he like him? Did he ever, like, in the first place?

"Deku, this is… you have to see how weird this is, right?" Ochaco says. She sits back down on the bed, shoulders drooped, looking defeated.

"Ocha, come on. You're my girlfriend. That hasn't changed, has it? I'm sorry I didn't tell you earlier. This has all been…" Izuku waves his arms and gives Ochaco a defeated look. "This has all been a lot."

Ochaco pauses and sighs.

"Yeah. I guess having your mom get remarried, and it be to your high school crush and former bully's dad, and having to move out of your childhood home must have been stressful. I'm sorry for freaking out." Ochaco smiles and ruffles Izuku's hair, affection clear on her face. For some reason, it makes Izuku feel like absolute shit.

"Lets grab dinner and drive me home?"

So they do. By the time Izuku gets back, its late. He doesn't know how he's supposed to sleep in this house. He doesn't know how he's supposed to sleep in this room. He feels like he's falling apart and has no way of holding steady. He quickly gets undressed and climbs into bed.  He rubs his face with his hands and glances at the bed across the way from him.

He fucking hates his body for being so aroused by being pushed around by Kacchan. Hates that these memories keep springing to the front of his brain, unhelpful and embarrassing. Hates that all of a sudden, he's super uncomfortable around his girlfriend, who has been nothing but a godsend to him. Hates that everything he has ever wanted just happens to be a few feet away, and he can't have it.

Hates that maybe, some little tiny part of Izuku thought that one day, they're going to run into each other again, Kacchan would sweep him off his feet, and they'd live happily ever after. Together. How many times has Izuku daydreamt about running into Kacchan at the airport, or years down the line working together? Didn't him and Kacchan deserve a little meet-cute, rekindling moment? Not this hot mess that his life has inexplicably become?  

Having thoroughly upset himself, Izuku slinks out of the room in order to sleep on the couch.