The Hamada brothers had been in a lot of tough situations, mostly caused by Hiro's inability to know when to quit. Whether it was bot-fighting or, hell, even talking, Hiro was constantly getting the two of them into messes. This moment was no different, though Tadashi couldn't give him all the blame. It could be blamed on a variety of things: video games, fate, Tadashi's dick.
Okay, so maybe that last one was a little more to blame than the rest.
Tadashi could feel a droplet of sweat slowly sliding down his neck. Already the room was hot with the heat of a San Fransokyo summer. Hiro's near proximity was only making his skin feel warmer. Dark eyes stared at him expectantly, that cheeky grin of his becoming slightly nervous as the silence stretched. What had Hiro said to him again? It had been lost in the sound of blood rushing from his head to his - well… to his other head. Another moment passed before he was able to pull his attention away from the weight of Hiro straddling his lap enough to speak. Even then it was only a halfway mumbled "What?" that made it out.
The look of exasperation on Hiro's face was simultaneously adorable and arousing. "You won. I'm yours. For the day, nerd."
He couldn't help the slight twitch of his hips at the sound of that, and Hiro couldn't ignore it. The young genius smirked at the flush that was covering Tadashi's face. Something about teasing his older brother was so satisfying. Annoying him had always been entertaining, but this… this was so much better. Hiro watched Tadashi's chest rise and fall a little faster, felt his lap tilt up against him and the slight squeeze of his hands on his hips. His brain just derailed. There was no going back. In a swift motion he jumped off his brother's lap, snagging one of his hands and pulling him to his feet. "Alright, time's up. We're going upstairs."
"Wha- no, Hiro! Wait!"
The younger turned, a stubborn glint in his eye. "Come on, nerd. What are you so afraid of?"
Tadashi made a noise, halfway between a growl and a whine, and stopped resisting. He followed the other boy out of the living room. The video game was still playing on the screen but neither of them even noticed. The heated glances that were passing between them were enough to drive them both a little faster towards the stairs wanting to get to the end goal sooner. They were almost there, too, when suddenly the black-haired boy stopped and turned. The mischievous grin that Tadashi knew all too well was on his face, making him nervous in the pit of his stomach. "New bet! Whoever moans first gets to top."
Tadashi's eyes narrowed, his protective brother senses tingling upon hearing the casual way that Hiro had said that. He was too young to be so nonchalant about sex! What the hell was happening to kids nowadays? Obviously he needed to be more vigilant about what Hiro was doing on the computer at night. Who knows what kind of websites he was getting on? What kind of information he was getting? No, it was better if he got that kind of education somewhere else.
Somewhere like… Tadashi?
He managed an affirming grunt - his lower anatomy causing him enough distress that he just didn't care anymore as long as they got upstairs. As long as they got away from the prying eyes of anyone who would happen to walk in. Hiro, however, still didn't move. Obviously enjoying his brother's discomfort, he stood there and watched the impatience build. He observed the muscle spasms in the elder's chest and neck and lower regions. As the tension built, Tadashi began to look like he was going to either murder him or take him right there on the stairs. When Hiro finally did turn to head upstairs he started slow, taking his time on each step. He began swaying his hips as much as possible, even bending over at one point to stretch out his back.
A sharp slap on his backside, however, ruined things. Whether it was the sudden stimulation on his hot skin or the sharp sting of pain - which he found oddly enjoyable - Hiro couldn't help the sound that ripped out of his throat. A soft moan that would barely hearable in most situations, but the silence of the stairs made it seem too loud. His muscles froze with the shock of the sudden realization of what had happened.
"What was that, knucklehead?" Tadashi was suddenly pressing against Hiro's back, their bodies flush. "Did you say something?"
"N-no!" Now Hiro was the one that was flushed and stuttering. "I just… race you upstairs!"
The eyes of the elder Hamada followed his junior upstairs, lingering on skin.
But it was undeniable and Tadashi couldn't help the flutter of excitement in his belly at the thought: Hiro had moaned. He followed quickly after that, slipping through the door and shutting it behind him with a solid click. For a second he forgot to turn the lock as well and had to turn back to double-check that no one could get in. The tiny snort that echoed from his side of the room at that.
His feet made quiet slapping noises as he hurried towards the divider that separated his side of the room from Hiro's. When he pushed it aside the desire that had been curling within his chest multiplied. Seeing Hiro stretched out with that annoying little smirk on his face made him want to throw caution to the wind and just leap into whatever this was. His instincts were the only thing holding him back. Tadashi crawled up onto the mattress and placed his arms and legs on either side of Hiro's small frame, resting there for a moment. His dark eyes searched his younger brother's face as he slowly lowered his lips and captured him in a gentle kiss.
"Hiro," he murmured against the other's skin, mouth wandering towards his neck. "We don't have to do anything you don't want to. We can take this slow. I don't want… I don't want you to regret anything, okay?"
Hiro, who was extremely distracted by the warm breath skating across his throat, took moment to respond. What exactly could he regret about this? He had wanted Tadashi for so long. No matter how hard he had tried to bury it and forget it, no matter how wrong it was, Tadashi was the only one who had ever caught the young genius' attention. He was the only one that could match him intellectually and inspire him to use his brains. Tadashi made him want to be a better person, made him want to look at things different, made him want to live. His feelings had been more than just brotherly for so long that Hiro didn't even know when they'd started to stray.
Needless to say, there was nothing he was going to regret. Not with Tadashi. "I can't regret you, 'Dashi. Just… stop being such a nerd and hurry up!"
Tadashi did the opposite of what was requested of him and pulled away. It took Hiro a few seconds to open his eyes that had been closed so he could better focus on the sensation of having Tadashi's mouth on him. What he saw nearly made him jump out of the bed right then and there, because he had never seen such a look of pure want on someone's face. It was overwhelming and all-consuming and just a bit sadistic. It made him feel like he was burning.
"Since I won the little bet on the staircase-" this made Hiro groan "- I guess I'm the one topping, right? Get ready, knucklehead."
Hiro bit back a moan as Tadashi tugged on his ear with his teeth. How the hell was this nerd so good at this? As hands started to wander it got harder and harder to keep himself quiet. Only two thoughts entered Hiro's mind, the name of his torturer and these words:
"What the hell have I gotten myself into?"
A/N: To be 100% honest, I didn't think I was going to continue this until I was in the middle of writing another prompt and I thought "You know what? People asked for it and this prompt be kind of great so why not?" and it was born. It was as close to smut as I felt like I could go... (/.\) It's barely even mature and I still feel like I need Jesus. I'm gonna go bathe in some holy water. Ciao, ducklings! I hope you enjoyed it!