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Izuku has never known a life without his Kacchan.
Ever since they were toddlers, they’ve been side by side. His mother always tells him stories of how they held hands everywhere they went when they were little, and how she thought they were so adorable. And Izuku doesn’t remember when he first took Kacchan’s hand, but he remembers the first time they kissed.
Or, really, all of the first times they’ve kissed.
The first time Izuku kissed Kacchan on the cheek was at the park after school when they were nine. It made his heart pound really fast and he almost cried. But then Kacchan smiled and kissed his cheek and everything was okay.
And then from there - everything was little kisses. Cheek kisses. Forehead kisses. Back-of-the-hand kisses.
The first time they shared a real kiss - lips on lips - was in middle school. Izuku walked Kacchan home from school and when they got to his door, Kacchan stopped and turned to him. His face was so red and his eyes looked angry. But Izuku knew that meant Kacchan was just trying to look tough. That he was nervous about something.
“What is it, Kacchan?” he had asked him. Kacchan had just muttered something under his breath in response.
And then, before Izuku could say anything else, he placed his hands on either side of Izuku’s face and pulled him in. When their lips touched, it was only for a few seconds, but Izuku remembers how it felt.
He finally knew what it meant to feel sappy romantic things like butterflies and fireworks.
It’s funny, kind of.
He can remember all of the first times that they’ve kissed, but he doesn’t remember ever asking Kacchan to be his boyfriend. Or Kacchan asking Izuku to be his boyfriend. They’ve just always been that way. And he loves it.
Just like how now, they’re hauling the last moving box into their apartment. The apartment that they share but never actually decided to cohabitate. Living separately after UA was just never a thought.
“You know what I just realized?” Izuku says out loud, once they’ve got their hands free and the door closed.
“Hmm?” Kacchan mumbles, already looking like he’s ready to unpack. Typical Kacchan - always motivated to get things done! One of the many things he loves about the man.
“I don’t think you ever asked me out,” Izuku laughs, sharing his thoughts. Kacchan just deadpans and then shakes his head.
“And?” he chuckles. Izuku just shrugs.
“I don’t know, I guess it doesn’t matter. I was just thinking about us and it occurred to me that we never officially started dating,” he says, very matter-of-fact. Kacchan just scoffs and flicks him in the ear.
“You’re such a nerd,” he teases. “What, you want me to ask you out?”
“Uh, yeah, maybe,” he shrugs.
“Fine. Wanna go out with me?”
“You said it too casually! That’s not romantic,” he says, trying to sound serious, but he can’t help the laughs that bubble up from his chest.
“Oh, you want romance, huh?” Kacchan asks, raising an eyebrow.
“I do,” he shrugs.
Kacchan sighs and pushes him back against the closest wall. Izuku giggles as Katsuki stiff-arms the wall next to his head and looks him right in the eyes.
“I said romance! Not kabedon,” he teases.
“This is peak romance, what are you talking about?”
Izuku tries to wiggle away, but Kacchan catches him around the waist. It results in a tickle-induced struggle until Kacchan ends up on his back on the floor with Izuku pinning him down. He inhales sharply at the sudden compromising position.
Because, while they’ve had many firsts in their time together . . . sex has not been one of those.
And it’s not because they don’t want to. Izuku definitely wants to.
It just, surprisingly, hasn’t come up.
At UA when they lived in the dorms, their friends would tease them about spending time in each others’ rooms. But all of their jokes were off-base because nothing ever happened outside of making out and maybe one instance of accidental dry-humping.
“Hey,” Izuku breathes, looking down at his boyfriend. Kacchan is so beautiful. He has pretty eyes and surprisingly soft hair. His cheeks are still tinged a little pink. “I love you.”
“Love you, too,” Kacchan sighs, his body relaxing as his hands rest against the tops of Izuku’s thighs. Izuku shivers at the touch.
“I’m happy that we’re living together now,” Izuku tells him. Kacchan nods, his hands moving slowly up and down Izuku’s thighs.
“Yeah?”
“Mhmm.”
“We get to share a room,” Kacchan reminds him. “And a bed.”
His heart flips over in his chest as he thinks about the queen-sized mattress on the floor of the master bedroom. They haven’t even bought a frame for it yet. An errand for tomorrow, perhaps.
“Yeah, we do,” Izuku nods, looking down at Kacchan’s hands.
Despite the fact that Kacchan is the person he’s most comfortable with, he feels nervous. His stomach twists and his throat aches as he tries to think of what he wants to say. Of how to get his point across without sounding pushy.
“Maybe we could . . . “ his voice trails off a bit and his hands stop moving. Izuku clenches his eyes shut.
“Hmm?”
“We could - ah, fuck,” Kacchan scoffs, his words cut off as his phone starts to ring. “Get up, I think that’s my dad.”
Izuku sighs and reluctantly stands while Kacchan sits up and answers the phone. He looks around at the small living room - their living room. One of the boxes has a label for the bedroom, so he picks it up and carries it down the hall. It’s not much - not yet, anyway.
The mattress is on the floor, and they have a full sized dresser and a bookcase, but that’s it. It’s all they need for now. He sets the box down and stretches out on the mattress. His heart flutters in his chest as he thinks about being curled up with Kacchan at night. Every night.
It makes him want to cry tears of joy.
“What are you doing?” Kacchan appears in the doorway, arms crossed over his chest.
“What did your dad want?”
“Just seeing if we were done with all the boxes. Mom wants to bring us dinner or some shit tonight,” he sighs. “Answer my question, nerd.”
“Oh,” he says. “Just laying down and thinking about you.”
Kacchan snorts but walks the rest of the way into the room and plops down next to him. Izuku’s skin suddenly feels hot as he remembers where their conversation was headed before Masaru called.
“So, where were we?” Kacchan grins.
“What?” he chokes. His boyfriend rolls onto his side scoots close enough to drape his arm around Izuku’s waist.
His chest feels heavy as Kacchan leans over to connect their lips. And then he promptly melts. Because he knows how to do that. He’s an expert when it comes to kissing Kacchan.
As he moves his lips and presses into their kiss, he lets his fingers wander up Kacchan’s arm until it pauses to rest on his bicep. Kacchan is so warm. And he smells sweet and musky and it makes Izuku’s head spin.
He will never get tired of kissing this man.
But then Kacchan does something a little different. He lets his hand slip down in between their bodies and palms Izuku through his jeans. It’s not bad. Definitely something that Izuku likes. But it catches him so off guard that he can’t help the yelp that escapes his throat.
In a panic, he sits up, tearing away from their embrace.
“What’s wrong?” Kacchan asks, sounding genuinely concerned. Izuku takes a deep breath and shakes his head.
“N-nothing, nothing’s wrong,” he chokes. “It’s fine, I’m just . . . I’m nervous, okay?”
Kacchan’s eyebrows furrow together as he sits up.
“Nervous? Why?” he scoffs. He leans back on one hand and uses the other to rub slow, gentle circles against Izuku’s back. “Since when do you get nervous around me?”
“Ah, it’s not you,” he promises, immediately. Never Kacchan. He takes a deep breath, trying to ease the pit in his stomach. Realistically, he knows this kind of reaction is irrational. Kacchan has been his partner in all things throughout his entire life. He knows he has no reason to be nervous.
And yet here he is.
“Then what? You don’t want to have sex?” he asks, finally dropping the word. “Listen, if that’s not something you’re interested in, we don’t have to, okay? But I don’t know what you want if you don’t talk to me.”
“I want to do it with you, Kacchan. I do. I just get nervous for no reason. I get worried that you’re not going to like having sex with me or that something’s going to happen . . . and then there’s also . . . “ he trails off as his mind really starts to take a deep dive. “Is that going to be our last first?”
“What?”
“Our last first. Like our first kiss, our first date . . . our first apartment together, and then our first time having sex . . . what if there’s nothing new after that?” he asks, his bottom lip starting to quiver.
“Hey, stop that,” Kacchan says, cupping the side of his face. Izuku juts out his bottom lip as his eyes well with tears. And then Kacchan moves his hand to pinch his lips between his fingers. “No tears.”
“Yes tears,” Izuku mumbles.
“Well, they’re tears for nothing because guess what? There are still going to be so many fucking firsts, okay?” he says. Izuku sniffles. “Our first house. Our first pet. Our first uh . . . co-signed bank loan?”
Izuku can’t help the smile that cracks through his tears. Kacchan always knows what to say to make him smile. Before continuing on with his list, Kacchan reaches out and pulls Izuku back against his chest so that they’re laying down again.
“What else?” Izuku asks.
“What else? Shit,” he chuckles, kissing Izuku’s forehead. “Our first date night in a new city. First wedding?”
“As opposed to our second and third weddings?”
“Listen, I’m gonna marry your ass as many times as I want, got it?”
“Okay!”
“So . . . what do you say?” he asks, his hands roaming over Izuku’s back. He shudders at Kacchan’s touch. Because it’s like electricity, but at the same time it’s safe. And it reminds him that Kacchan is right - he has nothing to worry about.
Kacchan is his home.
“Yeah,” Izuku nods. “I um, I want to try, at least.”
“Let me know if we need to stop,” he says, his voice getting lower and more sultry. Izuku can’t find his words, so he just nods. He slides his hands to the back of Kacchan’s head and kisses him deeply.
Everything slowly falls into place. Their lips slot together perfectly, and Izuku gasps as Kacchan’s teeth graze against his bottom lip.
“You’re so sexy, Deku.” Kacchan pulls back just enough to tell him, and then gently rolls until Izuku is on his back and Kacchan hovers over him.
A breath catches in his throat as he stares up at the man he loves. Kacchan's eyes are full of love, and he knows them so well.
"I love you," Izuku tells him. And Kacchan answers by dipping down to kiss him, dropping his hips so that Izuku can feel the warm, hard press of his erection.
"Take your shirt off," Katsuki breathes, sitting up once more and removing his own. Izuku stares at him for a moment, shamelessly.
Kacchan is so handsome, his body so perfectly chiseled. His strong hands push up at the hem of Izuku’s shirt, nudging him to take the damn thing off already. Izuku wiggles out of it and tosses it aside, then holds his arms out in time for Kacchan to dip down and kiss him again.
Their bodies press together- warm skin against even warmer skin. Kacchan rolls his hips and Izuku can’t help the gasp that escapes his lips. It’s incredible - something that they’ve both felt before, but it’s different in a way. Maybe because this time, Izuku knows what’s coming next.
They separate once more to struggle with belts and zippers until they’re both completely naked. Izuku has seen Kacchan naked before, at least. He’s familiar with the way that his cock hangs slightly to the left when he’s hard.
“Hold on,” Kacchan says, crossing the room to one of the stacked moving boxes. Izuku sits up and watches him, idly letting his hand drift downwards to stroke his own member. He pulls his bottom lip in between his teeth as he watches Kacchan bend over to rummage around.
“What are you looking for?” Deku asks, just in time for Kacchan to stand up again and turn to him. In his hand is a bottle of personal lubricant. Ah, yes, they’ll probably need that.
Izuku sucks in air through his teeth as Kacchan kneels between his thighs. He’s half expecting to feel Kacchan’s cold, lubed fingertips at his entrance. But instead, he gets a large glob of the stuff smeared across his cock.
“What are you doing?” Izuku asks him. Kacchan just rolls his eyes.
“What does it look like?” Kacchan retorts, moving so that he’s straddling Izuku’s hips instead. Izuku’s heart rate starts to pick up again, and his chest flutters as Kacchan positions himself over Izuku’s cock.
He moans as his cockhead presses against Kacchan’s entrance. It’s tight. So so tight. But he lets Kacchan take control, sinking down nice and slow. Izuku keeps his hands resting atop Kacchan’s thighs while he desperately tries to steady his breathing.
“Fuck,” Kacchan mutters, wincing.
“What’s wrong?”
“Nothing, you’re just - holy shit, Deku,” he moans, jerking his hips and sucking in the last bit of Izuku’s shaft. Izuku cries out, too. It’s such a sudden movement, but damn it feels good. He gasps and his chest heaves. His hands rub up and down Kacchan’s hips and thighs and waist and fuck Izuku can’t get enough of him.
“Kacchan,” he whines, desperate to move all of a sudden. He bucks his hips ever so slightly, and he’s not sure what’s better - the way that Kacchan’s walls slide against his cock, or the lewd noises that Kacchan makes as a result.
“Wait,” he breathes. “It’s a lot.”
“Yeah,” Izuku agrees. They’ve barely started and Izuku already feels like he’s about to reach orgasm.
“It feels so much better than a dildo, fuck,” Kacchan moans. His cheeks are flushed pink, his eyes heavy with lust. It’s such a good look on him, Izuku thinks.
“Thank you?” Izuku chuckles. “You’re better than a fleshlight.”
“Since when have you ever owned a fleshlight?” he grins. Izuku just shrugs and sits up a bit so he can hold Kacchan in his lap a bit better. He definitely notices the way the other man shivers as they move.
“I never have, I just assume you’re better than one,” he promises. Kacchan slides his arms around Izuku’s neck, pulling him in for another kiss. Any worrisome thoughts from before are gone from his mind.
All he sees now is Kacchan, Kacchan, Kacchan.
“I’m gonna move,” Kacchan whispers against his lips. Izuku just nods and slides his tongue between his boyfriend’s teeth. Focuses on kissing him and nothing else as Kacchan starts to move his hips. He starts slow and easy, and Izuku can feel every little drag of his cock against Kacchan’s pulsing walls.
The kisses grow deeper and more desperate as Kacchan starts to pick up speed. Kacchan’s moans swirl against Izuku’s lips and it makes him feel like he’s high. His moans get louder, and their kisses get sloppier, so Izuku moves his lips to Kacchan’s neck.
“Fuck, fuck, fuck,” Kacchan grits, his hips jerking over Izuku’s cock. And Izuku loves the way he does that. The way he grinds himself over and over again, getting off on his cock. “Touch me. Fuck, touch me Deku.”
“Okay,” he breathes, his voice barely above a whisper. He holds one hand on Kacchan’s hip and uses the other to grip his length. The head of his cock already glistens with precome. It’s red, throbbing, threatening to burst.
Izuku massages his cock nice and slow, and it doesn’t take much longer for Kacchan to start seizing up and releasing spurts of white across Izuku’s torso.
“Holy shit,” he breathes, and Izuku can only nod because it’s just that hard to find his words at the moment. Watching Kacchan come undone like that is what does him in. It’s what drives him to grab Kacchan by the waist and start thrusting up into him.
“Ah, I’m gonna cum, Kacchan,” he cries, and Kacchan just nods, dropping his head against Izuku’s shoulder. Izuku lets out a nearly inhuman noise as he spills into Kacchan. He never could have imagined that coming inside would feel so incredible. It puts all the times that he’s come by his own hand to shame.
They both need a minute to slow their breathing, and for their groins to stop spasming. Once he’s ready, Kacchan rises from Izuku’s cock and immediately drops down next to him.
“That was incredible,” Izuku tells him. Kacchan just closes his eyes and nods.
“It was,” he says. “See you were so worried about firsts . . . today was our first time having sex, but it was also your first time topping. Next time could be your first time bottoming.”
“Yeah?” Izuku asks, trying to picture it in his mind - the roles reversed. Izuku riding Kacchan’s dick. Or maybe Izuku on his hands and knees with Kacchan behind. The point is, Kacchan is right. When it comes to sex alone, there are so many different things they could try.
“Would you like that?”
“I would, actually,” he grins, turning his head towards Kacchan. He gives him a soft peck against the forehead.
“Good,” Kacchan grins. “Now, we gotta unpack.”
Izuku rolls his head back against the pillow and groans.
“I don’t wanna,” he complains. Kacchan sits up and flicks him in the forehead.
“We gotta,” he teases. “I’m not living out of fucking boxes for a day longer than we have to, okay?”
“Fine, just . . . at least let us clean up a bit?” Izuku suggests.
“Sure, nerd.”
They’ve officially broken in their first apartment together with their first time having sex. A day full of firsts for sure. But, just as Kacchan had said . . . it’s really only the beginning. They’re set to have a life full of new and exciting experiences together.
And Izuku can’t wait.