Chapter Text
Shouto was a good older brother — wonderful, even. When he came home, he stopped by your room to help you with homework, ate dinner together, and spent a few hours watching movies, everyday like clockwork. It’d been like this since middle school and he wouldn’t have it any other way. He absolutely adored you, his little sister, and would do anything in his power to keep you happy. He never pushed any boundaries, never pressured you into telling him what was wrong when you were upset, let you have your privacy, and didn’t guilt trip you when you wanted to hang out with your friends for a weekend. Shouto was the ideal older brother: loving, protective, and understanding.
Something inside of him changed once he began attending U.A.. Sometime within his first year — or maybe even before that — his feelings began to shift somewhere...sinful. Somewhere between his first and third year his brotherly love shifted into carnal desire. During study sessions, he’d found his gaze drifting from your face and down towards your chest and thighs. It was normal for guys to ogle at a girl’s assets, but that wasn’t something a brother was supposed to do at his little sister. As your older brother, Shouto shouldn’t be admiring the curvature of your body, the shape of your breasts, how soft the skin of your thighs looked. He shouldn’t feel the urge to reach out and touch whatever skin he could possibly get his hands on when he looked at you. It was wrong. So, so wrong.
Despite that, he couldn’t stop himself from thinking about you when he layed in bed at night with his hand down his pants, fisting at his hard cock. Shouto felt he was taking advantage of you in some way. It wasn’t your fault that you were so comfortable around him, not afraid to wear nothing but sleep shorts and an old shirt of his. It was his fault for seeing you in such an erotic light to begin with.
He didn’t want to imagine all the cute whimpers and whines you’d make as he shoved his face in between those plush thighs of yours. He didn’t want to imagine how you’d grip your hands into his shirt as he fucked you on his fingers. He didn’t want to imagine how you’d look in nothing but his hoodie as he buried his dick inside of you, how you’d moan out his name as he hit that sweet spot inside of your tight pussy, how you’d flutter around him as you came on his cock.
After he’d bring himself to completion, large waves would overcome him and he’d find himself drowning in the turbulent waters of regret. You were in the next room over, none the wiser of what your big brother was doing. This was disgusting. He was disgusting. Shouto couldn’t find it within himself to push you away and distance himself, though. He still loved you with all his heart. He couldn’t stand the thought of how heartbroken you’d be if your precious Shouto-nii didn’t even want to be around you.
There’d been many nights where he weeped into his pillow, the guilt too much for him to handle. Like this night, for instance. He’d got himself off to the thought of you while showering moments before he crashed onto his bed, the tears already cascading from his mismatched eyes. There was a knock at his door and soft footsteps padded on the floor, coming to where he was sprawled out face down on his bed. A weight made itself known on the bed near his legs. A soft hand came to rest on his bare shoulder blade, “Nii-san?” Shouto cried even harder. He wanted to tear himself away from your touch and yell at you to leave his room but he craved nothing more than your comforting presence.
You leaned over him, keeping one hand on his back and the other moving around to his clavicle. With as much strength as you could muster, you pulled him up and into your arms. Despite how his mind screamed at him not to, he didn’t hesitate to settle into your warm embrace, burying his face into your neck and wrapping his strong arms around your torso. Your fingers ran through his damp peppermint hair, smoothing out any awry strands and untangling any knots. As his cries turned to sniffles with the tears far and few between, you rested your cheek on the crown of his head and moved your hand up and down his back in soothing motions.
“Are you okay, Shouto-nii?” Your voice was just hardly above a whisper. He tightened his hold on your and shoved his face further into your neck. If he started talking, he was sure to cry some more. Shouto didn’t like this, being so vulnerable in front of you. He knew you understood that everyone had their moments, but he didn’t want you to see him like this.
He shook his head, his hair tickling your skin. He wanted to stay like this forever, being held in your arms and holding onto you tightly. Being like this with you was the most peace he’d gotten in these past 3 years of lusting for you. Shouto felt normal and not like some sick freak. He almost whined like a child when you moved his head away but relaxed when you cupped his face in your small hands, thumbs tracing back and forth over his cheekbones. His much larger hands came up and held yours there, basking in the feeling of your soft skin on his face. His eyes slowly met yours and he found himself lost in pools of (e/c). Without thinking, he turned his face into your hand and lightly pressed his lips against your palm, keeping his eyes on you the entire time.
Your innocent smile and sweet gaze didn’t waver once. You must’ve perceived it as an innocent gesture, the same as when he’d kiss your forehead or when you’d kiss his cheek. Nothing more than a peck shared between family. To him, this was all much more intimate than a love between two siblings but he could never outwardly express that. This was something he’d keep locked up inside himself. Shouto leaned forward and pressed a kiss to your forehead. He pulled away and tucked your hair behind your ear, “I’ll be alright. Don’t worry about me.”
“Okay,” You were hesitant. “but don’t hesitate to come get me if you need anything, okay?” It sounded like you were trying to scold him which made him smile. You were just so cute. He nodded. You stood up from his bed and walked back to his door, “Night, Nii-san. I love you.”
“I love you, too. Goodnight, (Y/N).” Again, he was alone in his room, left to wallow in his regret. Shouto rested his elbows on his knees and cradled his face in his hands. He caught a glimpse of the hard-on he was sporting in his sweatpants. He groaned. He just couldn’t catch a break, could he? Not that filth like him deserved such a thing.
Shouto just hoped you hadn’t noticed and that if you did, you thought nothing of it. That you didn’t even know what a boner was. He had serious doubts about that, though. You had to know about arousal and all that jazz. What if you didn’t though? What if you were oblivious to such things. His dick twitched at the thought. The idea of you not knowing a thing and being so innocent made arousal run through his veins like fire on gasoline. In that moment, he wanted nothing more than to corrupt you.
For the second time that night, Shouto came to the thought of you writhing in pleasure underneath him.