10

The honeymoon phase.

Katsuki's heard that term a couple of times, mostly from his buddies when any one of them establishes a relationship with more significance than the 'pump and dump' variety. He's personally never experienced that phase. He finds himself stuck at…well, fuck, the Splenda Asteroid phase? It's sweet, nice to look at, and fulfills you for the moment but it goes so fast that sometimes you can barely appreciate it. And, it always leaves a bad taste in your mouth.

Katsuki didn't want anything more than that. It fit him. It was uncomplicated. Katsuki liked uncomplicated. Some of these hopeless twinks that he's hooked up with expected him to be, what, emotionally vulnerable? To date them and text them and cuddle them after rocking their world? Hah.

Not to throw the 'child of divorced parents with an estranged mother' card around, but maybe Katsuki hasn't necessarily had the best role models when it came to love or romance or commitment. Hell, the only person he's ever… l…lo…loooooo…. Look, the only person he's ever had feelings for was somehow the same guy that he's treated like shit most of his life. The same guy that he struggled to show a morsel of affection to for the two years that they were involved in high school, and still failed miserably, considering the little fuck not only didn't come with him to Boston, but never visited, never called, never texted, and got a fucking girlfriend (not that he was still bitter about any of that. Get fucked.) The same guy that just happens to be his fucking step-brother. The same guy he spent all night making out with and touching under the covers on a Hawaiian vacation with their parents, who, oh, happened to be two feet away.

Katsuki liked uncomplicated.

This situation?

This shit is complicated. Extremely complicated. He's fucking summited the Mount Everest of Complicated, corpses of fucked up relationships littered around him as cautionary tales. Kaminari and Shinsou being one of them, of course. What that idiot jock thought he'd get out of a relationship with a fucking philosophy major with perpetual bags under his eyes, he'll never know.

Not that he'd ever admit it out loud, but for Deku, he'd do it again. He'd do it a thousand more times. He'd fucking do anything, as long as he gets to wake up, entangled in the arms of his not-so-little-anymore green nerd. He could do without hastily pushing away, the nervous glances at the sleeping couple to their left, the unfamiliar look of trepidation, the shadows in Deku's emerald eyes, that dirty and inherent sense of guilt that he's doing something wrong even though, objectively, he knows he isn't. He isn't, right? Definitely not. Probably. Maybe?

But, fuck. Katsuki's never fucking stepped down from a challenge before, and he's sure as fuck not starting now.

So he's not so sure what to call this – is it the honeymoon phase? That dumb, floating-hearts-around-your-head hopeless unwavering affection and devotion that he's overflowing with for the little green nerd has to be something. The honeymoon phase on a honeymoon, with your not-boyfriend who is your step-brother who you have been secretly or not so secretly in love with since you were four?

What? What did he say? Goddamn it, Katsuki. Not the L word. Keep it together.

"Where are you guys going?" Deku asks as, without really telling either one of them anything, Masaru and Inko start to head out the door.

Inko turns around and flashes them both an excited smile."We have an appointment for a couple's massage at the spa! Do you boys think you can keep yourselves busy for an hour?"

Keep themselves busy, they say? Katsuki's got a couple ideas. The second that door shut behind them, Katsuki is on Izuku like white on rice. He's prying his pants off, eagerly sucking up Izuku's soft member into his mouth.

"Whoa, whoa, hold on!" Izuku calls out, blushing hard, pushing against Katsuki's shoulders. But the pushing seems half-hearted, and Katsuki can feel the rapidity of the growing erection that he's lathering in his tongue. With a wet 'plop,' Katsuki pulls the dick out of his mouth and looks up at Deku, eyebrows furrowed. Its adorable that his step-brother's face gets that red as they make eye contact. Deku averts his eyes immediately, fidgeting with his hands. Its precious. Its like the beginning all over again.

"We got an hour. No holding on."

"Kacchan, please. I'm not – I haven't…" Deku stammers out, but his erection isn't speaking the same language, and Katsuki feels the shorter man's legs shake under him. Deku lets out a breath, like he's not able to cobble together a coherent string of words to form a sentence. Its like watching anal beads being pulled out – one by one, painful, yet somehow so satisfying. One of the guys that Katsuki had hooked up with was super into toys, and, well. He wonders whether Deku would be down to play.

"I haven't…. with a guy, since you."

Katsuki stops his insistent hand rubbing along Deku's taint, eager mouth peppering his shaking, muscular thighs that he can't seem to keep his eyes off of. That very admission opened up some kind of floodgate in Katsuki and shit, if he wasn't already hard, blood just fuckin' Trojan Horse'd itself into his dick. He's ready to go.

"What?" Katsuki whispers, kisses getting progressively wetter. He grins devilishly as Deku pants above him, hands threading through his blonde hair and grasping, as if to steady himself. A tell-tale sign that he's getting overwhelmed. Oh, fuck. Katsuki fucking missed this.

"But you're such a bratty little cockslut. I just don't believe you haven't taken it up the ass in three years."

Without waiting for a reply, Katsuki darts back up and picks Deku up, bridal style, the other man too surprised, it seems, to flail or fight against him. Pants around his ankles, flushed and sweaty with cock at full attention, Katsuki figures that this sight would be fucking hilarious if anyone was to see it.

He tosses Deku onto their shared bed and climbs in after, on his knees. He makes himself comfortable between those thighs, and plans to plant his flag there, claiming this continent as his own. The skin there is startlingly pale compared to his thighs, just below where the line his swim-trunks would end. He forgot how easy it was for Deku to get a tan, and how easy it was for him to burn. That browned skin is so fucking tantalizing, damn near golden, so sexy. Katsuki wants to lick it. But he'll hold himself back. Just for now.

"You're so gross, Kacchan! I'm not- I'm not - I, uh… well, my ex did. Um. Peg me a few times." Deku sounds a little less incredulous and a little more curious. Like he's discovering something he didn't really realize about himself.

Katsuki's movements stop and he furrows his eyebrows. The inexplicable feeling of acid climbing up his throat, his stomach flipping and clenching of teeth definitely tells him one thing. He's angry. Which is pretty fucking stupid. He shouldn't be sexually threatened by a 5'1 girl with a strap, right?

Of fucking course, she dumped Deku. And he cried over her. Meaning that this whole thing could be a fucking… rebound. He might be thinking about her when they fuck. Katsuki isn't going to stand for that. Deku is going to remember exactly who is fucking him. He's gonna fill Deku up with his cock so good, there won't be any room for a single other thought in that nerdy peanut brain.

Katsuki grips at Deku's thighs bringing the smaller man closer to his face. No one is going to see here, right?

Unintentionally rough, Katsuki puts his mouth on Deku's hipbone and sucks. He licks, sucks, nips, his other hand stroking absently just below his cock, just below a point of stimulation for Deku. He's not going to fucking give him the satisfaction. Not fucking right away.

"Kacchan!" Deku calls out, pushing against his shoulder, but not hard enough to mean it. Katsuki leans back, appreciating the dark, purple, spit-covered bruise already forming on his hip. He darts a quick eye up to see Deku's reaction, to be caught up in the image of his step-brother with his neck tossed back, chest heaving with stunted breaths. Deku's hand forms a fist against his shirt. Dive back in he shall, then.

"And? Was she better than me?" Katsuki's lips move a little closer to the leaking cock, enough that Deku can definitely feel his humid breaths against the base. Enough that he knows shivers are likely running up the little nerd's spine.

"Why are you making it into a competit – ah!" Katsuki dives right back in, suctioning the delicate skin into his mouth, teeth biting in harder this time, soft tongue caressing the injured skin, giving Deku a second to equilibrate before sucking even harder.

"Answer the fucking question, shitty Deku. Who fucks better?"

"Kacchan, please. Just touch me. Holy shit, oh my god, just touch me." Deku's voice is high, shaking above Katsuki as his mouth skirts along the base of his pretty dick. He maneuvers around it, finding Deku's other hipbone, and bites down, hard. The man yelps, but does nothing to stop him, hand moving from his shoulders to his hair. Katsuki preens a little when the fuck actually grabs into his hair and starts caressing and massaging his scalp. Good. The idiot is still into the same shit. Cute little masochist.

"Not until you answer my question, bitch. You thought I'd bless you with my cock and let you cum without putting in any work?" Katsuki laughs, letting the air from his breath linger over the tip of Deku's leaking cock.

"I – I – I don't know!!! Its been three years! Fuck, Kacchan! You might suck now! Just show me!" Deku's voice whines and a tinge of anger flares, before Katsuki siphons through the words. Classic Deku. He's doing something to get a rise out of him. He wants Katsuki to be rough. Katsuki breathes in deeply, giving his dick a pep-talk. Whelp. Upward and onwards. With a fluid motion, Katsuki hooks Izuku's knees through his arms, acrobatically bending the other man. Without proper ceremony, Katsuki dives right in, tonguing roughly against Izuku's puckering hole.

"Kacchan! Stop! What are you –!" Katsuki grips into Deku's thighs tighter, before pushing his tongue inside, wetting the rim with as much saliva as he can muster. The taste, the scent, the trembling of Izuku's thighs next to him. He's in fucking heaven. He can do this all damn day. But they only have an hour. Katsuki glances at the clock. Shit, 40 minutes. Better get the fucking show on the road, then. But not before he lavishes Deku's cute asshole with his tongue, slipping in just enough to make the smaller man gasp before licking up further, to tease his taint, his contracting balls, and of course the base of his perfect dick.

"Kacchan, please, we don't have time, just let me – please, please –" he hears Deku beg for something non-specific, but he knows. Oh, he knows. But why the fuck is his little Deku complaining? All he's doing is lavishing him with attention. What a brat.

"There's two dozen slutty bottoms in Boston who would fucking pay to be where you are. Don't fuckin' feel so high and mighty." Oh, if Deku thinks he's going to rile up Katsuki, he's gonna rile that little bitch right back.

He knows how jealous Deku gets. He lets out a self-satisfied smirk and, Deku, previously laying hopelessly in the bed, dissolving under his touch, bolts up, painfully pulling his own hair. Waves of pleasure careen down his spine. Fine, maybe Katsuki's a little bit of a masochist too.

"How many?" His surprisingly strong hand grabs Katsuki's jaw, bringing their faces close together. Katsuki searches those eyes – dark, blown, the deep darkness of a placid lake from where he might never return, furious and dangerous. He always knew that Deku had it in him. The little fuck has a monster inside, slumbering and ancient, that could make even Katsuki tremble. Oh yeah. Katsuki, every now and again, likes to poke it with a stick. Just to get that sliver of fear up his spine.

Katsuki smirks, just a tiny angle of the corner of his mouth, before Deku is smashing their lips together, more a hit than a kiss. Its all biting, teeth, pushing and pulling, tongue forcing itself into Katsuki's mouth, claiming everything as it's own.

"The fuck is wrong with you, Kacchan?" Deku growls at him. He pulls hard again against his hair, arching Katsuki's neck back. Katsuki shudders as harsh teeth graze against his jugular. In some primal part of his brain, Katsuki think that Deku might have bitten in, ended the life of his prey, destroyed him as he rightfully deserved. Deku's hands are on his hips, pushing him back onto the bed, and to Katsuki's endless surprise, the half-naked man is straddling him, thick thighs pressing into his sides almost too painfully.

The tears in his eyes, though, are unexpected.

"Huh? What did they do better? Did they fuck you better? Did they ride you better? What did I do, Kacchan?"

Its a startling contrast to the emotional voice coming from the man as he grinds his ass into Katsuki's erection, staring him dead in the face like he'd break himself open on his cock if he asked. Its confusing. Its arousing. Its making Katsuki very fucking upset.

"You're mad at me?! You had fucking relationships! People that fucking loved you! Meaningless sex is meaningless sex, but you fucking…" Let someone in. Let someone love him. So what? So Deku never cared that way about him? Never saw him as more than a sexual outlet? Never saw him as a viable romantic option? Because he's a man? Because he's his step-brother? What? What was it? What made Deku fucking… move on so easily?! Katsuki feels angry tears prickle at the back of his eyes, and he hides them with his own arch up, smashing their mouths together once again.

Deku meets him, all passion and fire and fury, tongue leaving sloppy wet lines along his lips, drool pooling in the corners of his mouth. His hair is standing all over the place, he's an absolute mess. He's so beautiful, Katsuki doesn't know what to do. His heart aches with it. He needs to show him. He needs to… needs to do with his body what his fucking idiot brain can't.

"Do you have…?" Deku asks, pressing their foreheads together hard, looking him straight in the eyes like he's peering straight into his soul. Past his soul. Into the trashbin at the back of his mind where he tries to get rid of things he's ashamed of. Like the fact that none of those other sexual conquests did anything but make him miss Deku. Which made him try again. And again. And a-fucking-gain.

"Top pocket of my bag. Condoms too."

Katsuki may or may not have purchased lube and condoms first fucking chance he had after they got to the hotel, because if he had to share a bed with fucking Deku, he needed a distraction. Preferably some stupid dude that he can bang in his hotel room for the rest of the week, so his sexual frustration doesn't get taken out on his very off-limits step-brother. Or so he thought.

Deku scrambles over to his bag, coming back in seconds with the offending agents. He stares down at the condom, then back at Katsuki.

He knows what it means. A silent question. We never used to have sex with condoms. Yeah, sure, fuck. They didn't. But now they've both been with a ton of people. And Katsuki hasn't been tested in the past month. Suddenly, those one night stands make Katsuki feel very dirty. Which sort of enrages him further. How dare Deku fucking make him feel bad? What was he supposed to fucking do? This is all Deku's fault. He's the one that didn't – goddamn it. God fucking damn it.

He doesn't change his expression, but Deku doesn't falter. He opens the pack with his teeth all smooth, like he's a goddamn expert. Katsuki realizes with a start he probably is. Probably done it plenty of times to his own dick. Because Deku's been fucking girls. He's been sleeping with women. Jesus fucking Christ. The nausea hits Katsuki again, rage mixed dangerously with desire, a bomb waiting to go off.

"Get the fuck up here," Katsuki motions, taking the bottle of lube. Izuku scoots up, and Katsuki pulls his head down, trapping him in a kiss. As skillfully as he can, he dumps some of the lube onto his fingers. He'll have to prep from the back, which isn't fucking ideal, but if he lets Deku get off him his brain is going to fill with images of his Deku having sex with women. And they've got 25 minutes to make use of this erection. No going soft now. Get your head in the game, son.

Its sloppier than Katsuki would like. Ideally, he'd open him up nice and slow, his legs spread, blindfold on his eyes, hands tied up to the bed as he fucked slowly, finding that sweet spot his Deku loves so much, and fucking into it until the other man was crying, begging for his cock.

But, what-the-fuck-ever. None of this shit is ideal. Katsuki slicks up his fingers and ignores the contracting of his chest as his Deku, his, moans into his mouth as his fingers reach around and penetrate him. Fuck, with these thighs, its harder to reach to the back of him, and Katsuki fumbles awkwardly, fucking more shallowly than he likes to. He's not even fucking reaching the prostate. Goddamn it.

Deku doesn't seem annoyed at all. He's pushing back impatiently into his fingers, his mouth losing contact and trailing down his jaw, his neck, back to Katsuki's mouth. He's almost frantic with it, biting into Katsuki's lips, letting out needy moans into his mouth, half of which just sound like his name, over and over and over again. Katsuki's fucking high with it. Is this what sex is supposed to feel like? Jesus fucking Christ, Katsuki's almost forgotten what it felt like to be overtaken with desire. But he's fucking remembering it now. Jesus, Deku. He's wanted him for so long. Only him. Always, only him. He speeds up his fingers, a third finally penetrating the muscular rim, and Deku pulls away from his mouth. Katsuki can only watch his stunning step-brother straddle him, glazed eyes focused on his face.

Katsuki almost can't watch. Deku hooks his fingers into the elastic of his pants, grabbing his boxers along for the ride, and pulls. His throbbing cock springs out. Deku visibly swallows, hands reaching out to touch him like he's winning an Oscar or some shit.

Katsuki knows his cock is top notch. Grade A, prime time beef. The size has been an issue with getting cups and jockstraps that fit him properly, plus when he had accidental boners in school there was no fucking way he'd ever be able to hide it. Whatever fucking genetic lottery he won to get his massive cock is clearly a fucking godsend, because he'll gladly have many more uncomfortable showers with his (straight) teammates ogling his junk if it gets him the privilege of seeing that look on Deku's face.

Its like the fuck found a picture of Virgin Mother Mary on his cock. He's staring at it, hands caressing it like something precious. Deku looks back up to Katsuki with some kind of elated wonderment in his eyes, and Katsuki can't help but smirk back. Yes, little brother. Katsuki wants to say. That's all for you.

Seeming to have finished having a conversation with himself, or praying over his dick, or whatever weird shit that Deku was doing, the smaller man rolls on the condom and grabs at the bottle of lube, generously slathering Katsuki's dick. His cock sincerely twitches with anticipation. Katsuki's entire chest feels like its on fire. Fuck, he might be having a heart attack.

He keeps his eyes on Deku, on the sinewy ripple of his lean muscles, and, yeah. Worth it.

Holding on tight to his cock, Deku glances at Katsuki, then back down, and slowly guides his impatient erection towards his hole. It spiritually hurts Katsuki to see Izuku fucking flinching like that, even with only the head of his dick penetrating, goddamn it, it has been a while, and also physically hurts with how tight and suffocating his insides are. He reaches out.

"Deku, Deku, hey, hey, lets stop this. A different time. I didn't prep you right and – and our folks are gonna be back soon, I just –"

Red is met with furious, dangerous green. Katsuki tries to search Deku's face, looking for some kind of answer. The little fuck looks determined, eyebrows furrowed, though tears are already pooling in the corners of his eyes. A mix of elation and fear burn though Katsuki. He loves the fact that he can split Deku open on his cock. But he doesn't want to actually hurt the little fuck.

"I'm doing this, Kacchan." He says, finally, as with a very slow, breath-holding, chest pounding groan, his perfect Deku kebabs himself on his cock. When his perfect, incomparable step-brother is sitting at his base, Katsuki lets out his own breath, the clenching around his cock relaxing.

Oh, Jesus. Deku's fucking an idiot for being jealous of his one-night stands. No one, no one is like Deku. In any way, shape or fucking form. The view is – is amazing. They rarely had the opportunity to fuck on a bed, in broad daylight (probably almost never) and this? That sweaty green hair, curls tumbling over his eyes? Those blown pupils, the heavily lidded, lustful look? That fucking toned chest and abs? Where did those come from? And the tan lines. Jesus, the tan lines. The fucking hickeys he sucked into his hips. Shit, its all so hot. Katsuki actually has to close his eyes for a minute. He's not gonna blow his load after all this goddamn fanfare. He has to make this worth Deku's while. He has to be worth Deku's while.

Katsuki barely has time to gather his bearings before those muscular thighs get to work, and the all-encompassing heat slides up, bringing all her nerve endings on end. Katsuki opens his eyes wide to see his wonderful, perfect Deku, filled to the brim with his cock, thighs flexing beautifully next to him, groan erotically as he rams himself back down. Katsuki has to take everything in him to not move his own hips, let Deku take control.

Its fucking unbelievable. Katsuki feels like he's floating in a pool of honey. Every inch of him feels like its sparking, alive, his mind free of thought for the first fucking time in three years. He watches, slack-jawed, as his step-brother absolutely fucking ruins his life.

Deku rides him like that for a couple of minutes, leaning heavily against his chest, his hands splayed along his pecs for balance. When he meets Katsuki's eyes again, he looks desperate, eyes red and teary, entire face flushed with desire. He's not hitting the right spot, Katsuki realizes. Here he is, fucking having the time of his life, and his poor nerd isn't even getting his prostate massaged. Not on his watch. Katsuki would fucking love this to continue indefinitely, but they're running out of time. Fingers tingling, Katsuki grabs at Deku's shirt and brings their faces together. Deku stops moving as they kiss, and experimentally, Katsuki thrusts his hips up, to be rewarded with a gasp.

"Take me." Deku orders.

That's all the permission Katsuki needs.

Hell to the fuck yeah. Katsuki grabs Izuku's waist and rolls them. This isn't a bad view, either. Looking down on Deku, blushing and breathing heavy, shaking so badly, wanting his dick. Urgh. Fucking poetry in motion.

He grabs Deku's thigh, thrusts his leg into his shoulder, and fucking rams in. The cry that Deku lets out, overwhelmed and animalistic, is the ideal feedback. Keeping his angle, Katsuki pivots his hips and fucks Deku mercilessly, shaking the headboard of their bed, Deku's moans getting progressively louder, more harried, devolving into gasps. He's sincerely fucking crying, and it makes Katsuki feral. Katsuki closes his eyes again. Fuck. Fuck. Katsuki loves it when they can make noise. He even lets out his own moan, earning him such a heated look from Deku that he's just about sure he'll melt.

"K-Kacchan – I – I can't – we – please, please, please," each word bitten off with a thrust, Katsuki can barely keep the elation off his face as he sees Deku growing more desperate, frenzied by the second.

"What? Use your fucking words like a good little slut and," Katsuki slams into Deku. "Tell. Me. What. You. Want."

"Please, please, let me cum, please…" Deku pleads, eyes unfocused, drool forming in the corners of his mouth. Its so fucking cute.

Katsuki has to pat himself on the back. He's lasted for – he glances at the clock – a solid ten minutes. Definitely not great, but. He was sure he was gonna blow his load the second Deku looked at him wrong. At least he got to hear the nerd beg. God, Katsuki loves it when he begs.

"Yeah, baby? You want to cum? You want to cum while your step-brother fucks you?" Deku's eyes shoot open and Katsuki fucking bites his tongue, wondering where that shit came from. He's even more surprised to see the playful smile on Deku's face, and the fact that the fuck actually arches his back. Katsuki leans down and takes one nipple into his mouth, biting gently, before finding Deku's mouth with his. He takes his other hand and puts it on Izuku's bouncing cock. Fuck, the thing feels like its going to explode. His balls are already so contracted, the fucker might cum without being touched. Katsuki would like that very, very much. He shakes his head at himself. Next time.

"Please, Kacchan, please, I want – "

Putting those core workouts to the test, Katsuki grabs at Deku's cock, releases control of the release he's been trying to keep at bay for the past 9 minutes and 59 seconds and smashes their lips together. He feels Deku's cock twitch in his hand and, rubbing over the head, Deku fucking bites into him as he cums, warm white cum spraying on his own chest. Whelp. That's too hot. Katsuki thrusts twice more before he's rocked with his own orgasm, white lightning blinding him for a goddamn second, before, boneless, he collapses on Deku, smearing his cum against his own chest.

Deku lands a kiss against his sweaty forehead and sincerely laughs. Katsuki arches himself up, disconnecting from his step-brother.

"Whats so funny, dipshit?"

"Should have figured the step-brother thing would be a turn on for you. Pervert." Deku teases. Katsuki laughs right back and lands a quick kiss on Deku's stupid lips before he hops up to dispose of the damning evidence still on his dick.

He's just about to bring a wet towel to clean Deku off when he hears a slam outside. Katsuki rushes out, only to see Deku sitting naked on the ground, eyes wide.

"Kacchan, I think you broke me," Deku says, bewildered. He points accusingly at his shaking legs. Katsuki can't hide the bubbling giggle and rushes over to help the love of his life get off the floor and clean up prior to their parents getting back to the room.

As the four of them leave that evening to go to dinner, the couple next door happens to be leaving at the same time. Their annoying parents, overly friendly as usual, strike up a fucking conversation. Katsuki sticks a pinky in his ear, digging around and leaning against a wall. He feels fucking great. He hasn't been this relaxed in years. Truly, Deku is the only chamomile tea he's ever gonna need.

"Oh, family vacation?" the couple asks, eyes darting from Inko and Masaru to Katsuki and Deku.

"Our honeymoon!" Izuku's mom exclaims. The couple next to them exchange amused looks, quirking their eyebrows.

"Wow…. Good for you, man! The stamina!" The man says, patting Masaru on the back. Masaru just stares after him, completely confused, as the couple walks off.

It fucking takes Herculian efforts for Katsuki not to burst out laughing. He wishes he had a fucking picture of exactly how red his little Deku can get.