Work Text:
Izuku's sitting on the couch, legs crossed under her with homework in her lap. Her brother, Katsuki, sits in a nearby chair, his own homework in front of him. She's just finishing the last sentence of her reading, stretching her arms above her head with a sigh. That's when she feels her brothers gaze hot on her skin. Suddenly conscious of how her panties and stomach have been exposed by the movement, she drops her arms and looks over at her brother. Katsuki isn’t looking at her but the tips of his ears are bright red, and she notices that his hands are gripping his book so tightly that she can see the paper crinkle. Izuku immediately forgets her mild embarrassment in favor of the curiosity that arises at her brother’s reaction to her movement.
He couldn’t feel like that towards her… or even if he did it had to be a fluke. Izuku would just have to keep an eye on her brother, observe him.
Before she could further develop her thought, she heard the front door open, signaling Mitsuki and Masaru’s return home. Dumping her homework on the coffee table, she jumps up to greet her parents. Stepping into the hallway, she watches as Masaru takes off Mitsuki’s coat.
Mitsuki grins at her and holds her arms open, “Hey sweetheart, come and give your mama a hug.”
Izuku throws herself into her mama’s arms, giggling as Masaru ruffles her hair, “Did you keep your mom and unruly brother in line while we were gone?”
At this Inko came into the hallway, apron tied around her waist, “Masaru are you trying to cause trouble?”
Izuku hears a smack over her head as Mitsuki whacks her dad, “Don’t compare our sweet angel Inko with our demon spawn,” she raises her voice, “Who isn’t even here to greet his hard-working parents!”
Disentangling herself, she watches as her mom moves in and exchanges kisses with both Mitsuki and Masaru. Her brother joins her in the hall, “Watch it you old hag, you and the old man haven’t even been gone all day. You both,” Katsuki glares at Izuku and Inko, “act like they’ve been gone for a month.”
Bumping her shoulder into her brother, Izuku looks up and smirks at him, “I bet you’ll miss them when they’re gone next week.”
Stumbling slightly, Katsuki shoves her back, “They wish I would miss them, I can’t wait till this break is over with and we get back to the dorms.” As she straightens up, Katsuki’s eyes drag up her bare legs, “You lazy or somethin’? Put some clothes on, you’re not five anymore.”
“Take your own advice,” Izuku pinches Katsuki’s nipple and dances out of reach of his retaliatory hands as he swings at her, “and put on a shirt.”
She sprints up the stairs to get ready for dinner before he can respond, so she misses the way his gaze hungrily watches her pantie clad ass as she climbs.
With the stress of the last couple of years of their children’s incidents during their hero training, the Bakugous decided a second honeymoon was well deserved. Both Katsuki and Izuku are home for a secret class wide break, and therefore unlikely to be caught in the middle of any villain attacks. With their children about to go into professional hero work, the Bakugous figured they might not get such a break again, and, with Masaru’s prompting, they decided to spend it on a romantic getaway.
Izuku is happy that her parents are getting some private time together. Often Mitsuki and Masaru’s jobs keep them busy and far from their family, and while Inko is able to stay home and take care of the house, she often misses her partners. With Izuku and Katsuki living in the dorms now, the house has been quieter than ever.
Izuku is also happy to spend time alone with her brother, and this week will be her last opportunity at extended time with him. After they graduate, they will be busy trying to break into the hero scene, and neither of them will have time to hangout.
Now that she thinks he might have the same immoral urges that she does, Izuku knows she has to find out. If she doesn't take this opportunity, she'll regret it for the rest of her life -- but a couple of fabricated scenarios should help her discover his true feelings.
Before the last couple of years or so their relationship had been… rough. Katsuki felt pressured by his parents to watch over and protect his quirkless sister. Running contrary to his need to protect Izuku, was her desire to become a hero and compete with her brother. This made their already strained relationship worse. Torn between his protective instincts and rage, Katsuki had lashed out. It had culminated in a fist fight between them in middle school, which had been laughably uneven at the time.
She still can remember how her arm was wrenched painfully behind her back, the sizzling of her brother’s quirk at the back of her head as he held a palm against her skull. Izuku had let out a whimper as he had pressed more of his weight against her beaten body to speak into her ear.
“If I was a villain I could kill you right now.” Katsuki’s breath had been hot on her neck and instinctual fear had her shuddering at the manic tone of rage in his voice. She had broke out in goosebumps, and under the fear she felt something hot in her belly at the power her brother was holding over her.
“You understand that right? If you don’t get these ideas of being a hero out of your head that is exactly what will happen. You’ll be killed,” Izuku felt him shift his body behind her, “or something worse.” Katsuki’s voice was low and husky as he growled at her. Before Izuku could react to the threat, her brother jumped off her back and stomped off.
It had taken her almost an hour to get home, and when she did Masaru had taken her to the hospital where an x-ray had found a fractured rib. Izuku had refused to tell her parents who had roughed her up, but the explosion marks had spoken for themselves.
She had to beg her parents to still let Katsuki take the hero entrance exams, and they only truly relented when she started to cry.
That night, while she was in bed, Izuku had heard her mom downstairs crying. When she listened on the landing she heard her mom shouting at her brother. It had been the first time Izuku had ever heard her mom yell.
After all three of their parents had given him a verbal lashing, Katsuki had been barred to his room, except for school and breakfast and dinner, for a semester. His isolation hadn't helped their relationship. They didn't have a real conversation until months later, after the slime villain attack.
After a couple of physical fights and more than a few frank conversations over the last few years, their relationship had improved to the point that Izuku once again considered Katsuki her friend. He, on the contrary, refused that label, especially when their classmates brought it up.
Izuku wasn’t sure when her feelings for her brother had gone from admiration to lust, but she had known that, despite the pain that their fight in middle school had caused, it was a turning point for her. She still remembered how Katsuki’s body had molded to hers and the heat in his low words. Since then, she had often shamefully touched herself remembering that day.
Now though, it seems like Izuku might not be the only one who wants to be closer to her sibling, and she isn’t going to let such an opportunity escape her. After dinner she pulls out a small notebook, this one different than her hero journals, and decides to get to work.
First is to make sure that Katsuki actually wants her in that way. Izuku knows she would never be able to get the proud hero-in-training to just admit his taboo attraction, but there were other ways to gauge interest. As Midnight often advised her students, there could be a lot of information given away in a look. So Izuku takes their parents’ holiday as permission to wear the skimpiest clothing she has: shorts that had only fit before she started using Shoot Style, before her thighs and glutes had firmed up as she took on the strenuous fighting style, skirts that are so short they border on improper to wear in public, and, of course, her current sleepwear, which mainly consists of overly large shirts stolen from her brother, and panties.
Cleaning up the table after lunch, Izuku makes sure to bend at the waist, pretending to scrub at a particularly stubborn stain on the table as her brother walks back into the room after dropping off the dishes in the sink. A second after hearing her brother walk in, Izuku hears him stop for a moment, then she hears him start walking again as he continues into the dining room. When he enters her line of sight, Katsuki’s ears are bright red and he looks uncomfortable. Izuku marks it in the positive column.
Another test occurs after an intense workout. Katsuki had refused to spar with her while they were at home, certain that her recklessness would bring their house down around their ears. Luckily for her, he hadn't refused her challenge as to who could run the fastest (her) or who could do the most pull-ups (him), and Katsuki even issued some of his own workout-based competitions. Izuku felt that working together helped them train harder and better, and she was always happy to accompany her brother during their daily workout.
During today’s training, Izuku mostly works with the heavy punching bag. Their parents had initially bought it for Katsuki, but in later years Izuku had gotten more use out of it. Sometimes Katsuki would hold the bag as she worked on some of her heavier blows, and then she would spot him as he did his bench-presses. Now she is cooling down, slowly working through different kicks and punches. Her focus right now is less on power and speed, and more on form. Izuku’s mind is distracted as she watches Katsuki perform some complex yoga moves. Katsuki seems to be focused on holding a great amount of his body above the floor in a contorted pose. Izuku watches as a bead of sweat travels along his bare back into his workout pants. Slowing to a stop, Izuku feels herself lick her lips as her brother fluidly moves to another form, the strain he’s under only hinted at by the slight shaking of his frame. As he starts with his ending poses, Izuku busies herself with gathering her things, her water bottle catching her eye. Waiting until she knows that her brother has his eyes on her, Izuku upends her water bottle above her head. Cold water runs down her short hair and face, drenching her workout bra. It feels good, taming the heat from her workout and from watching Katsuki, and leaving Izuku energized. She feels her nipples harden from the icy water that's soaked through her top. As Izuku screws her water bottle shut, she glances down at her chest. The thick material of her sports bra barely shows off her hardening flesh, but when she looks up, Katsuki's eyes are darting from her jaw, to her neck, to her chest. It feels like several minutes before Katsuki realizes what he is doing. His eyes meet hers, and for second he's quiet, apparently at a loss for words. Then he explodes to life.
“What the fuck you think you’re doin’? Huh? Just dumping water all over the gym, you gonna clean up that mess? I know Inko didn’t raise us to act like wild animals.” Katsuki seems to almost panic as he quickly walks out the gym, shouting back at her as he goes.
Well that wasn’t subtle. Izuku thinks as she follows her brother out and heads to the shower.
The rest of the day finds Katsuki barred in his room, apparently needing to catch up on his studying so he doesn't fall behind his number 2 spot.
After the way Katsuki had stared at her this week she is sure that he is at least attracted to her.
Why? Izuku doesn’t know.
She isn’t as pretty as many of the other girls in her class. Izuku is often called plain, and compared to someone like Momo or Ashido she feels like it. She keeps her hair short out of necessity. With her training regimen, Izuku would rather have an extra 30 minutes of desperately needed sleep than have to tame her long hair.
Then there are the scars, countless ones from self-inflicted injuries as well as those dealt to her by her enemies. In particular, her right arm is heavily scarred, with a chunk of her upper arm missing, leaving behind shiny, twisted scar tissue. Her fingers on that hand are crooked and misshapen.
She isn't often bothered by how she looks. She leads the life of a hero, and these scars show her dedication to her path. In instances like this, though, when she thinks about how much more attractive Katsuki is, with his almost perfect skin, his faint, thin scars that contrast with the thick red lines that decorate her body? She suddenly feels inadequate in her own body.
Despite her own insecurity on the subject, she knows what she had seen.
Now she needs to get Katsuki to act.
React might be the better word. Izuku thinks over her plan the next day and comes up with a couple of scenarios. The first of which has her barging into Katsuki’s room. Katsuki had been spending more and more time alone in his room as their parents’ vacation went on, much to the annoyance of Izuku.
As Izuku starts rummaging through Katsuki’s laundry, he slams his books down, “What the fuck are you doin’ in here nerd?”
“I’m missing a … piece of clothing. I wanted to see if mom accidently mixed it in with any of your stuff.” Izuku lets herself blush as she awkwardly rubs the back of her neck.
“Did you throw any of your laundry in with mine? You know Inko has to use special detergent for my laundry, it’s fuckin’ wasteful to put your stuff in with my clothing.” Katsuki frowns, “What is it? One of your braces or something? It could be in the drawer with the compression wraps, I wouldn’t have noticed it in-“
“No!” Izuku stops herself and lowers her voice, “Uh, you probably would have noticed it.”
“Well then what is it?” Katsuki has his hands on his knees, watching her.
“Uh, it’s red?” Izuku pretends to hesitate in saying more, knowing it will drive him crazy.
“It’s a red what, you dweeb?” Katsuki seems to be having fun watch her embarrass herself.
“It’s uh, it’s uh…thong.” Izuku looks down at the floor, hoping to seem embarrassed.
“A…” Izuku swears that she can hear her brother go offline. “A fuckin’ what? Why do you even have one of those? Who do you have it for? What fuckin’ extra? That half and half bastard? I’ll fuckin’ kill him-“
“No! I don’t have it for anyone in particular.” Which was true, she hadn’t bought it for anyone. She had just seen the set while shopping and had been drawn to it. Red was her favorite color and the lacy texture had seemed so pretty. When she first tried it on she had felt… sexy.
“Why would you need somthin’ like that.” Katsuki muttered. “Just forget about it, get outta here. I needa study.”
Izuku shuffles her feet, “It was expensive though, I don’t want to lose it.”
“Well it’s not in here, so you can leave.” Katsuki points to the door.
“Please Kacchan, help me find it.” Izuku looks at her brother from under her eyelashes, “You know mama won’t let me hear the end of it if she finds out about it.”
Groaning, her brother pushes himself up from his bed, “Whatever, but you owe me for this Deku.”
After about a half hour of searching, Izuku lets Katsuki find the lingerie. She had left it peeking slightly out from under the couch where it would have looked like it got dropped on it’s way to the washing machine. Izuku watches from the corner of her eye as he finds it, his hand rubbing the silky lace between his fingers. She waits, curious to see if he will- Katsuki brings the cloth to his face briefly, pulling in a deep breath. Izuku feels her pussy throb as she watches her brother huff the crotch of her dirty underwear like a pervert.
Izuku made sure her scent would be thick on the lacy thong by wearing it as she got herself off.
More recently, Izuku had taking to stealing some of her brother’s dirty laundry, shoving his boxers into her mouth as she touched herself. Izuku was happy that it was a habit that they apparently shared.
“Deku, I found them.” Katsuki tosses the panties at her and abruptly turns to leave.
Izuku quickly crosses the living room and burrows herself under her brother’s strong arms before he can leave. “Thank you so much Kacchan,” Izuku presses the full length of her body against his, and as she brings their hips together she feels the beginnings of hardness between Katsuki’s thighs.
Looking up at her brother, Izuku smiles, “I’ll have to repay you somehow. I’ll do whatever you want.” Izuku feels like she might be laying the act on a little thick, but most of her research had been based on cheesy porn plotlines and she doesn’t know what else to do.
For a second Katsuki looks shocked, his pupils are blown open, lips slightly parted; Izuku could swear she feels the slightest of twitches coming from his hips. In the next second, he’s pushed her off, “I’ll think about what favor you owe me. Gotta go work on the homework you interrupted.”
As Katsuki storms out of the living room, Izuku grins. Her brother might not have broken yet, but she can feel that he might be close to losing his firm grip on his self-control.
Izuku makes her next move that night, right before bed. She comes in wearing one of Katsuki’s threadbare old t-shirts that’s so large on her it almost hangs off her shoulder.
Katsuki, already in his pajama bottoms, looks up at her in irritation. “You need any more help nerd?”
Izuku shrugs, “Yeah, I think I might have pulled something on my back today. Could you look it over? I can’t really feel back there.”
Izuku watches Katsuki swallow as he notices her state of undress. “Yeah,” his voice is rough, and he clears his throat, “I can look at it.”
As Katsuki sits back, Izuku crosses the room and sits on the edge of his bed, pulling her shirt over her head as her back faces him. The only thing that she’s still wearing is her pair of panties. She hears Katsuki harshly pull in a breath, and after a moment she feels him put his hot hands on her bare back.
Gently he smooths his palms down the expanse of her back. Izuku feels goosebumps pebble her skin and she squeezes her thighs together at the rush of arousal she feels as Katsuki’s fingers trace over her skin. His touch is gentle but firm, exploring the notches in her spine and the muscles of her back. The pressure of his touch slowly increases, and he pulls his hands down the span of tense muscles that make up her back. The heat and the steady firm pressure feels so good and Izuku can’t help but moan as the tension in her muscles gets released.
Over the quiet sound of his hands, she can hear the click of his throat as he dryly swallows.
“Uh… have I touched it yet?” Katsuki’s usually brash voice is quiet and low.
Izuku lets out a deep sigh, “Yeah, I might have just been a little tight. But I think this-“ Izuku pulls one of his stilled warm hand and places it over her ribs, “is a little tight too.”
As Katsuki places his other hand on her front, he’s forced to move forward. He re-positions himself, and Izuku feels his bare chest pressed along her back. Her brother’s breath is hot on the back of her neck and she can hear his heavy breathing as Katsuki starts to move his hands over her ribs.
His fingers gently work the muscles between her ribs and Izuku can’t help but whimper as the tender flesh is pressed on. Katsuki’s breathing gets harsher as his hands move. Carefully, Izuku shifts forward, the bottom of her bare breasts lightly skimming her brother’s hands. Then, after a moment, just as carefully, she moves her body back, resting against Katsuki’s chest. His heart is pounding so hard, Izuku swears that she can feel it through her back.
As she lets out a soft sigh, Izuku arches her back and tilts her head back onto Katsuki’s shoulder. Looking at his face, Izuku notices that Katsuki’s eyes are hungrily consuming her chest.
With a soft moan Izuku opens her mouth, “Thank you so much Katsu-nii, I feel so much better.” Under the pretense of shifting her weight she rubs her ass against his crotch, her brother’s rock hard cock obvious with the movement.
“You’ve always been so good with your hands Katsu-nii, and they feel so wonderful and warm.”
Katsuki meets her eyes, his only half opened. A groan rattles his chest and his hands firmly smooth down her flanks. Goosebumps ripple on her skin and she feels her pussy throb, slick dribbling out of her sex.
As his hands sweep upwards, Izuku snaps and grabs her brother’s wrists. Firmly holding his wrists she pulls his hands up to cup her breasts. “Katsu-nii I need your hands here. Can you make me feel good here too?”
Her brother freezes for a second then he lets out a rough shuddering sigh. His hands squeeze her flesh, then pull and twist at her nipples, high pitched whines making their way past her lips.
Katsuki buries his face in her throat, tonguing at her pulse. As he starts to speak his words are muffled in her flesh, “Fuck Izuku … Fuck… You want this?” Katsuki rolls his hips against hers, and she can’t stop her moan. “You want this, sweet girl? Huh? You want your Katsu-nii’s cock?”
Izuku clings to her brother’s forearms, “Please Kacchan, please give it to me!”
Taking one hand from her breast, he holds his arm over her lower stomach, pinning her between his legs as he humps his cock against her ass. “Shit! You feel how hard you’ve made your brother? I’m going to make you fuckin’ scream if you don’t stop me right now.”
Turning her head, Izuku whispers into her brother’s ear, “I’ve been touching myself, thinking about you,” she shudderingly breathes in, “since we were in middle school. Please, do your worst.”
Izuku has bulked up over the years, her muscles putting almost all her classmates to shame. So when she finds herself flipped onto her back on the bed, she’s a little surprised. Katsuki is looming over her, his eyes dark as he takes her in. He leans down, his breath puffing out hotly over her mouth, and pauses. Izuku surges up when he fails to move closer, and mashes her lips into his.
The kiss is too consuming to be anything other harsh and messy. It’s not her first kiss, there was Shoto in her second year. It’s not Katsuki's either, that was taken by Kirishima when she tried going out with Shoto. It feels like it is though, she’s so nervous and excited, and the way Katsuki pushes into her mouth feels so different from the careful slide of lips between her and Shoto. She swallows the extra saliva that is flooding her mouth and pushes against Katsuki’s lips. As he shifts, Izuku nips and pulls at his lips and he lets out a low groan.
Izuku remembers a time when they were younger and traded little innocent kisses between the two of them until their parents, lightly chastising, told them to stop. This is only like that in the love it expressed, the intimacy, but it's hot and filthy and it’s leaving her breathless.
She keeps trying to twist her tongue around his, imagining how she would lick the head of his cock. Katsuki keeps thrusting his tongue in and out of her mouth, fucking into her, and she whimpers with the movement. They break apart and Katsuki rests his forehead on hers, breathing heavily.
“You’ve been such a fuckin’ tease since we’ve been home. Your slutty little panties, wearing my clothing. Fuck. I’ve been wanting to ruin you.”
Katsuki stares into her eyes as he talks, and Izuku can see the barely held restraint in them. Thinking about the last couple of years, Izuku can only remember her brother looking her in the eyes a handful of times, and only during the rare moments they laid their emotions bare.
Izuku draws a steadying breath.
“Well I wasn’t the one walking around without a shirt since he started high school.” Izuku teases back.
“Hah- What?” Izuku watches as Katsuki steadily turns more and more red. He’s sputtering, trying to formulate a response.
“Yeah Katsu-nii, it’s so distracting when I’m trying to workout or study and you just walk around bare chested!”
Izuku takes her hand from the bed and gropes at a pec. Then she pulls and pinches at a nipple. Katsuki whimpers at the stimulation.
“You know how lewd your chest looks? It makes me wanna play with it till you cry.”
Katsuki swears and knocks her hand away. “I could say the same about you nerd.”
Dragging both of his palms up against her stomach, he cups her breasts. “Do you know how distracting these are? Everytime we have to fight in civilian clothing I almost get killed ‘cause I can’t stop watching these tits jiggle.”
A burning heat works across her face, up her neck and ears. Izuku knows she’s bright red. Izuku whines, “Nooo Kacchan.”
“Yeah Deku, makes me wanna kill any extra that looks at you.” Katsuki leans down to mouth at her nipple, moaning as he tastes her.
"Fuck, so soft," he says as he sucks on the sensitive flesh, flicking his tongue over the stiff peak of her nipple. Izuku whimpers and moans at the attention, her voice growing louder than his groans. His other hand is spread, palm down, on her stomach. He firmly pushes against the plushness that hides a steel core, then slides his hands around to grip at her waist.
Her own hands have wandered from covering her embarrassed face, one gripping at her brother’s shoulder and the other pulling his spiky hair. She pulls him in closer to her soft breast, and his groans and grunts become even more muffled with the pressure on the back of his head. Opening her legs slightly, Izuku presses her thigh between her brother’s, firmly pushing against the hardness she finds.
Instinctively, he ruts his cock against her thigh, nipple slipping out of his mouth as he whines, face pressed between her breasts.
Izuku wants to squeeze him close against her, wants him to cry and whimper and scream for her. She’s always thought he was the most handsome when he cried. Izuku loves seeing how his face flushes, how he’s unable to control his expression, how he’s unable to stop messy tears from dripping down his face, and how he looks at her like she’s the only one who can understand his feelings.
It's a temporary urge, they're both too eager, too impatient to bring that desire to life.
After a second, Katsuki rips back from her, breathing heavily, “Don’t- hah- think you can pull a fast one on me.” Kissing down her stomach, his bright red eyes meet hers, “I’ve wanted to do this for years too.” Soft hands tug down her panties, slick connecting them to her for a moment before they are pulled all the way off. For a second, she feels hot breath above her core before she feels the broad swipe of a tongue.
Mouth falling open in a sigh, Izuku opens eyes she didn’t realize that she closed. Izuku sees a smirk and a partially opened mouth, already damp and shining. Hands spread her thighs, hooking her knees over Katsuki’s shoulders. Burying his head between her legs, she feels as well as hears her brother’s groan. What’s louder is the wet sound of him licking the sensitive flesh between her thighs. Every lick and suck overpowers the sound of her own pants and whines in her ears. With how his tongue wetly traces her folds, the feeling makes her thighs try to open further, ankles crossing behind her brother’s neck as she presses against his face. His palms smooth down the outsides of her thighs, stopping at her hips and ass periodically to squeeze and grope. When he flicks the tip of his tongue against her clit she clamps her thighs down, crushing his head between them.
Katsuki moans, and she can hear the sheets rusling. Looking down she sees the tight curve of his boxer-brief clad ass moving up and down as he humps the bed. The visual of a blond shock of hair buried between her thighs, hands gripping her hips, knuckles white, and the shuddering movement of her brother desperately trying to rub his cock against the bed is what tips her over. It's the most intense orgasm she’s ever had, and she feels every muscle squeeze tight. Warm wetness floods out of her with each contraction.
Izuku grunts at the force of her body’s pleasure. She still feels her brother licking at her core, furthering the electric shocks radiating from her pussy, until it becomes too much and she pulls at his hair until his tongue stills. After a moment he pulls against her thighs. Breathless, she lets her legs fall open, freeing her brother.
“You trying to fuckin’ kill me? I was about to suffocate with how tight you were clamped around me.” While the words are mocking, Katsuki’s voice is wrecked and he is still subtly grinding down on the bed.
His face is wet and glistening and if she had any energy left, Izuku would be embarrassed. Still slightly punch drunk, she laughs, “You’re soaked, Kacchan.”
“Fuck, you should see your cunt, Deku, if ya wanna see something soaked.” Katsuki takes one of his hands and smears it through the wetness on his face. He then proceeds to lick them clean. “Shit, I think you squirted.”
Izuku angles her head away from the hungry look that is roving over her bare form, shame finally rearing its head. “Sorry Katsui-nii. I didn’t mean to make a mess.”
Katsuki slams his head into one of her thighs, his voice becoming muffled, “You don’t even know how badly I wanna fuck you now.”
Wedging a foot under his chest, Izuku pushes Katsuki up and back until he’s on his knees. “Then fuck me Kacchan.”
With a snarl, Katsuki lunges back over her, arms bracketing her head, and smashes his mouth against hers. The familiar taste of her own arousal coats his lips and tongue, and she whines as he licks into her mouth with her own slick. As he leans further into their kiss, Izuku can feel the hot length of her brother's erection where it presses into her belly.
Pulling back from the kiss, Izuku hooks a leg around the back of his waist, further opening herself up as she pulls him closer to her. “Please, Katsu-nii I need it.”
Katsuki knocks their foreheads together, “Fuck, yes, okay.”
Pulling back, Katsuki rises to his knees, broad hands pressing her thighs back, “Hold your legs back, okay?”
“It’s fine, Katsu-nii.” With her intense training routine, the position barely strains her muscles.
Tracing the seam of her cunt, Katsuki lubes his fingers with the abundant amount of wetness he finds.
Izuku feels the blunt tip of her brother’s large finger enter her. It’s quickly joined by another and she can’t help but squeeze down on the fingers, trying to pull them in further. It doesn’t take long for her to be stretched. Back in her dorm room, she kept a small collection of vibrators and dildos to fill the aching emptiness that accompanies her arousing thoughts of her brother.
It seems like only a second later when Katsuki has three fingers in her, harshly pumping them in and out as squelching sounds fill the room. “Deku, I can feel how hard you’re squeezing my fingers.” Katsuki trails off with a faint whimper.
“Fuck, I’m going to split you open on my cock. Your cunt is gonna look so good around me.” Katsuki roughly pulls down his damp underwear, letting his cock spring free to slap against his stomach. The foreskin is only partially rolled down, leaving a wet pink head to peek out the tip. Izuku feels her mouth water. She wants to tongue that slit, to taste his precum.
She watches his stomach and thighs flex as he pulls off his underwear. A shiver overcomes her as her brother pulls his fingers through the slopping mess of her cunt and smears her slick over himself. As he tugs on his cock, Izuku sees him pull down and expose his angry looking cockhead.
“You still on the pill?” Izuku wants to ask how he knows that she is, but her brain can’t fathom asking that question out loud, so she just nods.
“Good, fuck, I wanna come in you, you good?” Katsuki seems to be grunting out the words, almost as incapable of speech as she is.
She nods again and Katsuki shuffles forward. Grabbing the base of his cock, Katsuki guides it into her cunt. The slide is smooth, thanks both to how much slick she’s made tonight, and the way her arousal has made her insides soft and pliant.
As he pushes further inside of her, Katsuki moves forward on the bed, shifting her legs higher over his chest until his hip bones rest against the back of her thighs. “Ready?”
Izuku can see the way he’s holding back. She’s so full and he feels so warm in her cunt, a low moan echoes in her throat as she tries to answer. “Yeah Kacchan. Ruin me.”
As if her words are the bang of a starting pistol, Katsuki pulls halfway out before slamming back into her, like he can barely stand to pull out much at all. She groans as he pushes against sensitive nerves inside of her, involuntary squeezing down on her brother’s cock at the feeling.
“Oh fuck, did that feel good Deku? It felt like a hand was squeezing me inside of you.” Katsuki narrows in on that spot, as if it were a weakness during a sparring session. Each brush over those nerves lights up her body with a sensation of pleasure intermingled with a need to piss.
Katsuki starts to increase the speed of his thrusts, but then he periodically slows and grinds himself against her insides. Slick is pushed out with Katsuki’s cock as he shoves it in, and she can feel it trickle down her ass. As he increases his tempo, Izuku can hear his balls slap against her, making her squirm in his hold. Each impact forces a breathless whimper out from between her lips.
Looking up at her brother, she notices his eyes focus on the way her breasts jiggle with each thrust. With her legs resting on Katsuki, her hands are free to cup and squeeze at her breasts. Using her other hand, she reaches at where her and her brother are joined. Izuku feels where Katsuki is thrusting into her, rubbing a little at his cock before gathering some slick onto her fingers. With her newly wet fingers, she teases at one of her nipples, pleasure shooting through her body with every slippery pinch.
Katsuki's gaze burns as he watches her hand move from her cunt, to her tit, to her mouth so she can suck the excess fluid from her fingertips. He pushes her legs further into her chest and starts slamming even harder into her. “You look like a little slut, Deku. What would all of your friends say if they saw you so wet, squeezing tight around your brother? What would they think if they knew you were choking for your dear Katsu-nii’s rock hard cock since you were a kid?”
Izuku whimpers at the filth falling from her brother’s lips.
“Hah, you would like that. Such a sweet little slut. Want me to tell all those extras why you won’t spare them a second glance? What me to tell your little boyfriend why you would have never been satisfied with anything his dick could do? That you were waiting for this?” Katsuki slams his hips into her and grinds, the sound of her slick squelching loud in the room.
“You want them to know how I’ve fucking ruined you for anyone else?”
Izuku convulses, she’s shuddering around the dick inside of her, letting out a chest deep groan with each cresting wave of her orgasm. Katsuki drives his cock in and out as her muscles pull out his own orgasm. He can’t force out anymore of his dirty thoughts and he stops speaking as he whimpers and shoves his cock as far into his sister as he can. His balls squeeze themselves empty as he spills his seed deep inside her. As her rhythmic contractions become to much, Katsuki pulls out and watches her clenching hole push out a dribble of cum and slick, which drips down her taint.
Katsuki drops down on her like his strings are cut, and Izuku wraps her arms around him as she shivers with aftershocks. As their breathing steadies, she pets at his head, hand smoothing his hair down only for it to immediately spring back up. The motion used to be a familiar one, when they were still young, before the world and their feelings drove them apart. Izuku had liked to play with her brother's hair. It was fun to watch how it always retained it’s spiky shape, and the movement often soothed the both of them.
“That was so nice, Kacchan,” Izuku kisses the top of his head. “My nii-san made me feel so good.”
“What are we gonna do, nerd?” The words seem like they should be teasing, exasperated, coming from her brother, but the tone seems hopeless.
Izuku pulls him further onto her chest. “We’ll figure out something. You know what All Might calls us, the Wonder Duo. There’s no way two heroes like us can’t find a solution.”
“Whatever, nerd. Don’t talk about All Might right after we fuck.” Katsuki pulls up some sheets to cover them, coming back up to lay his head on her shoulder.
“Kacchan, want me to get some stuff to clean with?” While she likes the wetness between her thighs as a nasty reminder of what they just did, Izuku knows that Katsuki cares more about stuff like that than she does.
Katsuki grunts, “No, don’t be annoying and move, the sheets have to be washed anyways. Also,” Izuku feels his big fingers pushing their mixed fluids back into her, “you think I’m gonna let you wash this out anytime soon? You’re lucky I don’t have something I can plug you up with.”
With that, Katsuki rests his hand on her lower belly and curls into her. Within a few moments Katsuki’s heavy even breathing signals he’s asleep.
Izuku groans, her brother’s last words having fanned her banked desire. It looks like she will have to wait it out to fall asleep.
It is comforting to know that her brother is still an asshole.