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Katsuki and Izuku have been dating for over a year now.
It’s weird to think about. Sometimes it feels like they’ve been together forever, that things have always been this good between them. Other times it feels like they’re still figuring things out, because at the end of the day they aren’t perfect, and neither of them have been in a relationship before. Most times, though, they don’t have to think about it. It’s just Kacchan and Deku, like it’s always been.
Katsuki found out he was a little back in high school. He was experiencing symptoms of age regression, did some research, and adjusted his life accordingly. He’s better off using littlespace to cope, so he didn’t bother fighting it. It’s just another gear in his system.
He didn’t intend for Izuku to find out. But, well, when you live with someone, there’s not much you can hide. He was bound to slip up eventually, and he did so in the form of a pacifier and a box of crayons sitting on the living room table.
For what it’s worth, Izuku handled the situation perfectly. He calmed Katsuki down from his anxiety attack, gently coaxed answers out of him, and then the bastard went and offered to help him of all things.
“Wait, what?” Katsuki had asked, sniffling.
“Doesn’t this normally create a second dynamic in relationships? The little and the... er, stand-in parent...?”
“Caregiver,” he corrected quietly.
“Caregiver? Aww, that’s so sweet! I like the sound of that, taking care of baby Kacchan-“
“Hold on, Deku. You’re not upset?”
“Why would I be upset?” He asked, tilting his head. “It keeps Kacchan safe. And it gives us the opportunity to do so much more stuff! Like coloring, watching cartoons... well, you know.”
“You really want to be my caregiver?” Katsuki questioned, shaking his head in disbelief. Izuku nodded eagerly. “... Okay. We have to set up some ground rules, then...”
That had been a few months ago. Since then, they’ve fallen into the roles of caregiver and little with ease. Izuku cherishes the time he gets to spend taking care of Katsuki and loving him in a completely new way, and Katsuki’s happy that he finally has someone that will help him in littlespace.
Currently, the two are at a party. Their manager insisted that they go to this event to schmooze with other heroes and maybe get a few interns to sign on to their agency. And while socializing and drinking and all that fun stuff definitely have their place in a hero’s life, sometimes it can be too much.
Like for Kacchan.
He never drinks at parties, too afraid to make a fool of himself in public. This means he faces the full brunt of his social anxiety with no inebriation to help soften the blow. Henceforth, he tends to start destressing in other ways; taking a quick walk outside, using Izuku as a human shield, holing up in the bathroom with his phone and playing mobile games...
Slipping into littlespace.
He didn’t mean to, really! It’s just that sometimes he can only take so much of adult life before he starts to regress! It’s not a conscious decision, it just happens!
He needs to pull himself together. Needs to put on a brave face and smile through the pain until Izuku decides it’s time to leave.
He doesn’t really register that, though. He just wants his paci, and his stuffed bunny, and Daddy. He’s tired and he feels like crying and he kinda has to go potty but everything is too loud and bright for him to process!!
“Bakugou!” A vaguely familiar voice calls out. He looks up to see Sero. “Hey man, how’s it going? It’s been a couple years, huh?”
“Hi,” Katsuki greets quietly, rubbing his arm self-consciously. “D’you know where Da- Deku is? I lost him.” Sero snaps his fingers.
“Oh, that’s right, you two finally got together! I totally forgot about that. I just saw him earlier... over there!” He says, pointing to where Izuku is talking to a young girl. “So, which one of you finally bit the bullet? Did you ask him out or did he-“
“Okay, thank you,” Katsuki interrupts him, making a beeline for Izuku.
“Yeah! So we’ve only got a few interns as of right now, but we can- oh! Hey, sweetheart!” Izuku greets, pressing his lips to Katsuki’s. The taller man wrinkles his nose (he does NOT like big boy kisses when he’s little) but doesn’t protest. “How’s it going?”
“I’m tired,” Katsuki says softly. “Can we go?”
“In a bit, Kacchan. This lovely young lady and I were just talking about her coming on for a work study! Isn’t that right?” He asks, winking at the girl knowingly. She laughs and nods.
“But Deku...”
“After this, honey,” Izuku says, although there’s a bit more force behind his words this time. Katsuki’s initial reaction is to tear up at the harsh tone, but he opts instead to huff and take a seat right next to them, pouting the whole time. “Sorry about him. Where was I?”
This is so dumb. Daddy’s supposed to know right away when he’s little, but he’s not even paying attention! He hates that stupid high school girl. All he wants is for Daddy to walk him to the bathroom and then drive them home so they can snuggle and watch a movie, but because of her they have to stay at this dumb party! It’s not fair!
As Katsuki pouts, he starts to squirm uncomfortably in his chair, and then he gets an idea. A yucky, bratty idea, but an idea that will get him home sooner nonetheless. So he stops squirming in his chair, and he lets go.
“Deku,” he says after he’s finished, tugging on his sleeve. Izuku gives him an annoyed glance.
“Almost done, Kacchan. We just need to get Aiko’s parents to sign a permission slip. She just texted them, they should be here soon.”
“I gotta tell you a secret,” he insists, tugging harder. Izuku sighs, but leans in close.
“What is it?”
“I had an accident,” Katsuki whispers, pointing at his soaked drawers. “We need’ta go home.”
“... Kacchan!” He hisses, flushing red. He immediately moves to hide Katsuki’s front from Aiko, straightening himself. “I’m sorry, but we have to go! Something came up!”
“I-Is everything okay?” She asks, eyes wide.
“Everything’s fine!” He assures her, taking Katsuki’s wrist and leading him away. “Make sure to call the agency tomorrow! Tell them that I recommended you!”
As he’s being dragged away from the party, satisfaction and pride settle into Katsuki’s bones. His plan worked! It was wicked, and a little embarrassing for both of them, but it got him what he wanted! Now he can tell Daddy that he slipped, and they can go home.
“Deku,” he starts. “I-“
“What the hell was that about?” Izuku snaps, pulling him out into the cool night air. “Kacchan, that was humiliating! Anyone could have seen us! You can’t pull something like that just to get your way!”
“Huh?!”
No no no, this isn’t right! Daddy wasn’t supposed to get mad at him!
“I know that that wasn’t an accident. You did that on purpose. You did it to get my attention!” He rips his hand away, staring Katsuki down. “Well, you got it, Kacchan!”
“I-I just wanted to go home!” He defends himself. “You wouldn’t listen!”
“So you had to piss yourself?!” He hisses, making sure to lower his voice for the last two words. “Unbelievable. You just had to be patient! You could have just driven off a work study student, and we really can’t afford to be doing that at this point in our agency!”
“But-!”
“You know what? I can’t deal with this right now. There’s too many people around,” he huffs. “Let’s go. We’ll talk about it when we get home. Where no one can hear.”
The car ride home is... not ideal. Katsuki starts bawling the second the engine starts, and when he refuses to answer Izuku’s questions, the radio is turned on to drown out his cries.
He’s still crying by the time they get home, which softens Izuku’s demeanor a little bit. Even though he did potentially publicly humiliate the both of them tonight, he’s clearly upset, and it’s his job as his boyfriend to deal with an upset Katsuki.
“Come on,” he says softly, holding the car door open for him. Katsuki sobs and shakes his head. “Kacchan, let’s go.”
“No-o-o!”
“Jesus Christ, Katsuki. I’m not gonna drag you inside. Get out of the car already.”
“NO!”
“Why not?!”
“Da-a-addy’s maaaaaaaaaaaaaaaad!” He wails, rubbing his eyes. Izuku’s heart sinks in realization.
“Oh, Kacchan. Baby boy, I’m sorry,” he breathes, pulling him into a hug. “I’m so sorry. I thought you were just being a brat. I’m sorry.”
Katsuki doesn’t respond, likely slipped too far at this point to even form a coherent response. Izuku holds him until his cries even out to a socially acceptable volume, and then he unbuckles him and leads him inside by hand.
“Shh, my baby, it’s okay,” he coos once they’re in their apartment, wiping the tears off of Katsuki’s cheeks. “It’s okay. I’m so sorry for yelling. That was very mean of me. I didn’t know that you were little, baby.”
“Da-addy... w-wet,” Katsuki whines, shifting in place. Izuku clicks his tongue and strokes his cheek lovingly.
“I know, angel. Why don’t we get you out of those icky clothes and then we can take a quick shower together? After that I’ll make sure to put a diaper on you, you can wear one of Daddy’s shirts and we’ll watch a show together, okay? Does that sound good?”
Katsuki nods, rubbing his eye with his fist.
Izuku makes sure to scrub them both down as quickly as possible, taking extra care to Katsuki’s thighs to make sure he doesn’t get a rash. By the time they’re done, Katsuki’s stopped crying completely, only sniffling occasionally. Izuku dries him off with a fluffy, warm towel and gets their pajamas ready.
“Daddy?” Katsuki mumbles around his thumb as Izuku helps him step into a pull-up.
“What’s up, sweet boy?”
“Kacchan’s sorry,” he says quietly.
“You don’t have to apologize, baby, it’s okay,” he promises, standing up to press a kiss to Katsuki’s forehead. “I thought you were being a brat so we could go home early, but you can’t help having accidents when you’re little. I was wrong. I’m very sorry for that.”
“No, Daddy’s not,” Katsuki admits as Izuku pulls one of his shirts over his head.
“I’m not what, baby?”
“Not wrong,” he says quietly. “I-I peed in my pants so we could leave the party...”
“... Oh, Kacchan,” Izuku sighs, pulling on his own pajama pants. “Okay. I understand why you did it, but you can’t pull stuff like that in public, baby boy. You know better than that.”
“M’sorry,” he whimpers, rubbing his eyes again. Izuku shakes his head, picking him up.
“It’s okay, baby boy. I messed up more tonight than you did, anyways. I shouldn’t have yelled at you like that...” He frowns and runs a hand through Katsuki’s hair. “But never mind all that. Why don’t I make you a bottle of warm milk, hm? I can feed it to you while we watch a movie, how’s that sound?”
“Good,” Katsuki sighs happily, letting his head fall against Izuku’s shoulder as the shorter man takes them into the kitchen.
After Katsuki’s done with his milk, Izuku pops a pacifier into his mouth, and the little snuggles into his Daddy’s chest so they can watch Monsters Inc together.
And later, when Katsuki starts tearing up because he couldn’t hold it and needs a new pull-up, Izuku doesn’t yell at him. He just cleans him up and helps him get changed, and they curl up again, good as new.
Yeah, maybe they’re still figuring things out. But they’re Kacchan and Deku! They’ll get the hang of it eventually.