A/N: Back again! This chapter does contain smut and is mostly from Izuku's point of view. THIS IS JUST A DADDY KINK. Bakugou is NOT in little space. If you're not okay with that don't read but I do thank you for your support still. Also contains voyeurism, somnophilia, and slight feminization. It's meant to be a little silly.
Izuku has always been a naturally curious child. He's observant by nature and he enjoys the intake of information he receives---loves to learn. He can't remember how old he was when he had actually started to keep his precious notebooks filled with knowledge on both heroes, friends, and foes alike. There is, however, so much he's still so very curious about.
Like the dynamic of Shouto and Katsuki's relationship.
He understands that Shouto is the caregiver and Katsuki is the little. He understands that Katsuki likes to bottom and Shouto prefers to be on top. Those were fairly easy concepts to understand. But how do they separate the two? Do they only have sex when Katsuki isn't little? If not, how does sex work when he's in that headspace? Does he understand what's happening? Does Shouto have to explain it to him? He wants to ask, but he'd have to do so while Katsuki's in his headspace to avoid being blown into the stratosphere. Even then, he may incur upon Todoroki's wrath to ask such an invasive question. So for now, Izuku gives up the idea of ever getting an answer.
That is, until he finds himself stuck in a fortunately unfortunate situation.
You see, he had been spending the day with little Kacchan per usual while Shouto went to visit his mother for the day. It hadn't been anything out of the ordinary for them during that time, save for the fact that they had spent the day in Kacchan's room and not Izuku's. They'd made pillow forts, eaten snacks, and binged Disney movies at Kacchan's request, ending the day with a bedtime story that Izuku made just for him.
The explosive blonde had been put to bed no later than 8:30PM after talking with Todoroki on the phone to tell him goodnight. He had assure Izuku that he'd be home before curfew to get him, not wanting to cause an episode again. Izuku managed to stay up until 9:30 before he, too, fell asleep in Kacchan's room, making himself comfortable in the nest of blankets and pillows on the floor while Katsuki curled up in his bed.
The sound of the door opening stirred him out of his slumber around ten.
It startled him at first until he remembered where he was, eyes opening just the slightest to catch a glimpse of Shouto's face caught by the light of his cellphone in the dark. He stops just short of where Izuku is sprawled out on the floor and smiles, stepping over him as quietly as he can as not to wake him. Izuku is grateful that he decides not to wake him up and send him to his own dorm this late. He's much too tired and is unsure of whether or not his limbs will take him there without incident so he closes his eyes again and sinks back into the bedding to go back to bed.
It proves to be a more difficult task than he'd like.
There's the constant sound of shuffling going on behind him at the desk where he assumes that Shouto is getting undressed and ready for bed. He can hear him make his way over to the bed, can hear him climb onto it before it falls silent. All he can hear is Kacchan's soft snoring in the blue-black dark of the room. Eventually, it lulls him back to sleep again.
For all of ten minutes.
He's stirred awake by what sounds like Katsuki's voice, a soft, pitiful whine spilling out. Izuku nearly jumps to his feet out of instinct---thinks he might be having a nightmare until he remembers that Kacchan's daddy is with him so he doesn't have to handle it this time but his thoughts instantly derail the moment he hears---
"Daddy~"
It's followed by a soft gasp and Midoriya feels his skin catch fire atop of the cool pillows as a loud squelching noise follows.
A-Are they...?
Is h-he...?
Surely not, right?
Izuku turns his head, barely able to see with the only light in the room being the luminous glow of the moon through the sheer material of Katsuki's bedroom curtains. There, on the bed, Shouto is hovered over Katsuki's body. The boy's face is still against the pillows, turned where Izuku can see how flushed he looks. There's no mistaking the way his mouth falls open with little wanton breaths, hips raised and sleep shorts pulled down around his thighs as his All Might plushy lays forgotten on the floor.
Right next to a bottle of melon flavored lube.
Izuku catches the soft hitch in his breath and prays that they can't hear him; he prays that they don't see him watching like some sort of pervert but for some reason he can't look away from Shouto pumping his generously slicked fingers into Katsuki's sleepy body.
"Shhh, go back to bed, darling." The dom whispers into Katsuki's ear, pressing kisses down his back as his fingers dig deeper into him. Another sweet whimper leaves the little blonde and he wiggles his backside. It's an invitation that Shouto takes, pulling his own hardened cock out of his boxers and lubing himself with the leftover lube on his hand and pressing Katsuki into the bed with a flat palm against his back. He pushes in with one fluid motion and Katsuki yelps, hips jerking away as Shouto's fat cock bullies it's way inside of him.
"But daddy, we c-can't."
"Why not?"
"C-Cause Zuzu's h-here, daddy---ah!"
Shouto grips Kacchan's waist his with his free hand, rolling his hips in a way that makes his baby's walls clench and his eyes roll back. "If you're good and quiet for daddy, Izuku won't hear you getting full of daddy's cock." He says, moving his other hand down to his waist to move him up and down his cock with harsh pulls. "You're so eager for it, too, hm? Your little cunt was all wet and twitching for daddy."
Izuku can feel himself getting hard. He wants to say something, wants to run out of the room and throw himself into a burning dumpster---never to be seen again but his body feels like lead and he's sure he'll never be able to live it down if they realized he'd been watching them.
"You opened right up for me."
"Cause 'm sleepy, daddy."
"Then go back to bed. I don't need you to be awake for this."
"But daddy---" the sound of Shouto's hips shifting and the loud, lewd sound Katsuki's walls make as the lube gets fucked out and around them overpowers the helpless little cries Kacchan let's out. Pleasure curls along his spine with Shouto's cock deep and heavy in his tummy.
"I'll ruin my pretty kitty's little cunt if I want." Katsuki squeezes and Shouto groans low, grinding his cock into Katsuki's sweet spot with a sharp clap to the backside. "Be a good slut for daddy and stay open for me. I'm going to pump you full of cum. You wanna have daddy's baby, don't you?"
Jesus H. Christ, Izuku never thought Todoroki would be so...
Lewd.
"Mmh, but what if Zuzu wakes up?"
"Then he'll get to watch me fuck your lovely pussy open."
A giggle from Katsuki's drooling mouth. Izuku thinks he almost looks cute like this---he would, anyway, if it weren't for the knowledge that he was being fucked right there in front of him.
"Daddy, you're so bad."
"Mmm, yeah, baby."
He doesn't stop, doesn't let up. In fact, the snap of his hips comes quicker, the subtle rocking of the bed picking up ever so slightly. Izuku reaches down to palm at his straining erection, biting his lip to hold his moan when Katsuki practically screams into his pillow. His toes curl, ass tilting upward as Shouto kisses and scrapes at his neck and shoulders as he pounds into him.
"Yes, that's my good boy. Your pussy belongs to daddy, doesn't it, kitty?"
"Y-Yes, daddy, only you!" Is muffled into the pillow. He's sobbing, thighs trembling as he struggles to keep his hips raised during the assault on his prostate. Izuku reaches into his shorts and strokes himself from under the blankets, breath picking up so heavy that his only saving grace is that Katsuki is louder.
"Does daddy's cock feel good in your tummy, hm?"
"S-So good!"
His hips cant back against Shouto's to meet his thrusts aggressively, the bed beginning to creak louder under the pressure.
"D-Daddy, I can't anymore---"
"Yes you can, sweetheart. You can hold it a little more and then daddy will let you have all the cummies you want."
Izuku's hand picks up when he sees Katsuki bite into his lip. He's trying so hard to concentrate on holding it but it's so hard with the way Shouto's holding him down. Shouto can't get enough of the way Kacchan's wet, yummy hole swallows him up, chest heavy as sweat drips down his chest and makes his shirt cling to his pecs.
"Your little cock is dripping all over the place, so cute." He says, reaching around to Katsuki's front to fondle his swollen cock. Izuku's own is dripping so much pre-cum that he can almost hear his slicked up pumps from underneath the blanket.
"There we go, lovely, you're doing so well. You can have your cummies, now."
Katsuki throws his head back, entire body going tight and taught with full body tremors as he whines and gasps with the force of his orgasm, spilling into the fabric of his shorts as Shout continues to fuck into him until he spills deep into his baby. He let's his weight fall forward onto Katsuki, burying his softening cock deeper inside as he catches his breath.
Izuku bites into his hand to muffle his own climax as it spills against his own sleep shorts while Shouto busies himself with pulling out and wiping the cum from Katsuki's thighs and hole with his shirt. The blonde boy has already fallen asleep again, no doubt pushed back into the world of slumber by the intense orgasm worked out of him. Shouto pulls up his own shorts and removes Katsuki's, pulling the blankets up over him in favor of walking all the way to the dresser to get more.
Izuku feels ashamed, yet incredibly turned on. He's never felt something so intense before---but he's also never been front row seat to a live prono before either. He feels sticky in his shorts and even more disgusting as he wipes the cum from his hand onto his shorts but he can't find it in himself get up. Not while he's sure Shouto is still awake and most definitely not while his limbs feel so heavy that he could sink into the floor.
"Midoriya."
Izuku freezes, eyes snapping open when he hears Shouto call for him. Should he play dead? Pretend he doesn't hear him?
"I know that you're awake."
Dammit!
"A-Ah..um...yes?"
"Did you get enough for your reasearch?"
Izuku's face lights up bright red.
"I-I-I'm not sure. M-Maybe I could take notes next time?"
Shuffling. Shouto's getting under the blankets with Kacchan.
"Next time?"
Izuku instantly backpedals.
"I-I-I mean if you were okay with that cause obviously I could only do that with your consent but it was hard to really memorize anything since I had to pretend to be sleeping so I didn't really gather anything to take notes on---"
"Sure, Midoriya." Shouto says, a slight chuckle in his tone. "Good night. I'll see you in the morning."
Izuku smiles at his friend.
"Yeah. Oh, and Todoroki?"
"Hm?"
"Please don't tell Kacchan about that."
"Oh, he already knows."
A/N: for those of you still confused, Bakugou was well aware of what Shouto was going to do before it ever happened, which is why Shouto tells Midoriya at the end that Bakugou already knew. Meaning that the whole thing was staged and fully consensual. I can't believe I actually have to keep explaining this but here it is for all of you to see. Thanks.