Lust : noun\ˈləst\ a strong feeling of sexual desire

The digital clock read 3:00AM in glaring red numbers, made brighter by the contrast of the dark bedroom. The early autumn night was cool like always. A light breeze rolled through the half-open window bringing both distant noise from the still bustling city and a chill. Hiro shivered and snuggled into his blankets, and then realized he was awake. But why? It couldn't be that cold. He slowly blinked as his vision began to focus and the shadowed figures of junk on his desk came into view. Yawning, he sat up wondering what had woke him up. Everything seemed fine and Mochi wasn't pawing at the door like he sometimes did when Aunt Cass cuddled him more than he liked. It was then that he glanced down and noticed the tent in his Kamen Rider boxers. A dark spot was slowly spreading throughout the fabric.

"Oh god, again?" he sighed to himself, glancing a bit guiltily at the gentle rise and fall of his older brother's sleeping form as he remembered what he was dreaming about.

In this one, he'd been sitting in Tadashi's lap, legs wrapped tightly around him and moaning as his brother bit painfully deep hickeys into his neck and shoulders. He wasn't going to deny it, he was absolutely in love with his brother. Well, love was probably the wrong word. Lust was more accurate. But how could he not be? Tadashi was perfect; smart and kind as he was attractive, and god was he attractive.

Far too often Hiro would steal glances of him in the morning when the two got dressed or when Tadashi came out of the shower, half-dressed or covered only by a towel. A glimpse of bare skin, of the muscle that years of robotics work had developed, would go straight to his groin and he'd bite his lip until it bled.

It was only natural after the first few times he got caught drooling like an idiot that Hiro built hidden camera bots for the bathroom and bedroom to stream compromising footage of his brother in various states of undress to his laptop, where a program automatically saved the files to the completely inconspicuous folder on his desktop titled "Tadashi's Hot Bod".

The morality of his attraction, be it love or lust, was of no concern to him. He knew he'd probably get over it when his hormones weren't changing so suddenly and if he didn't, it wasn't a huge deal. They were both male. Honestly, it annoyed him more than anything else. He knew that Tadashi would never indulge him, either too moral to break such a taboo or too protective over his baby brother to ever risk hurting him. So he fell back to his fantasies, curling up in his blankets and slipping his fingertips into the fly of his boxers.

He imagined Tadashi behind him and fabricated the feeling of warmth and weight against him. The slim fingers grasping at his hardening cock and the thumb smearing precum over the head were much too small for him to even pretend they weren't his own, but he could imagine Tadashi's voice in his ear, egging him on with sultry whispers.

"Come on, Hiro," he'd purr in a low, husky voice. His breath would blow hot against Hiro's cheek with each word, and he would shudder in pleasure on cue. "Touch yourself for me. Don't you want this? You love me right? You've always wanted this, so do it. Cum for me, Hiro."

"Oh fuck," Hiro groaned, voice cracking above a whisper as he tried so desperately to keep quiet. His hips were thrusting rapidly into his hand, precum spilling over and lubing up his fingers. His eyes rolled up into their sockets in pleasure as he thrust faster and created a thousand different fantasies at once.

Tadashi, rubbing circles over his hips with both hands. Tadashi, mouthing him through his thin cotton boxer shorts. Tadashi, soft hair tickling the insides of his thighs as he took Hiro into his mouth. Tadashi, Tadashi, Tadashi... Fuck me, fuck me, fuck me...

Hiro came so hard he cried. Fat tears rolled down his cheeks, puddling with the slight drool on his pillow. His body shuddered, and his hips made increasingly shallow thrusts as he rode out his orgasm. He knew that he had to stay quiet, but his senses were too clouded with pleasure that he couldn't help himself from moaning out "Tadashi..." When he heard bed springs squeak across the room, he lie horrified. The fear of getting caught temporarily stifled his libido. He thanked god that he was facing away from Tadashi. He might be able to fool him by lying still.

"Hiro?" Tadashi whispered through the dark. "You okay? I thought I heard you."

Hiro responded with silence, and after a good minute or two, he heard his brother lie back into bed and turn over. He sighed a silent breath of relief, blushing furiously at how close he'd come to getting caught. It would be kind of hot though, getting caught cumming to his sick fantasies of his big brother. Maybe that's what he'd think about tomorrow when Tadashi left Hiro at home to go to his nerd school.

He would come home early and find Hiro curled up asleep on his bed, wearing nothing but one of Tadashi's old oil stained hoodies from his high school robotics team. Hiro would wake and turn over, barely concealed in the dark cotton fabric.

"You're home," he'd sigh with a small smile. His lithe thighs would spread slightly when he met his brother's lusty gaze and he'd sweep his tongue subconsciously over his delicately parted lips. He'd silently plead for Tadashi's touch through his smoldering half-lidded stare, and for once in his life it would actually work and Tadashi would sit between his parted legs and slide his big hands under the hoodie, exposing him.

He would run his rough, calloused hands over his skinny chest until Hiro was positively writhing in delight. Tadashi would touch and tease his nipples into stiff little peaks, maybe even take one into the warmth of his mouth. Hiro would arch his back towards him and beg for more. "Is this what you want?" Tadashi would ask him teasingly.

Hiro would be absolutely sobbing with pleasure at that point. "Yes.. Oh god... aah.. yes... Please, niichan... please..." he'd cry as his hips desperately bucked up, aching for any bit of friction.

Tadashi would smirk in amusement at Hiro's enthusiasm, finger trailing the length of his stiffening erection and dipping into the beads of precum at his head. He'd bring the finger to his lips, and for a moment they'd be connected by the pearly strand. And then – Hiro felt himself getting hard once again.

I promise my smut writing won't be as cheesy if/when the full yaois happen. I just think Hiro would idolize Tadashi in his subconscious to the point where he's 90% wish fulfillment and not like himself at all bc that's what I do when I think about people I know irl. Idk, I just love Hiro so much bc small baby shota teen son and I project myself onto him. Like the "Tadashi's Hot Bod" folder is because I name my folders stupid shit like "husbandos" and "wink wonk".

-edit-

alright, so i'm sorry to say there won't be another chapter to this. I really tried, but I gave up because I honestly hate writing. I never feel like I'm good at it, but when I wrote this, the hidashi fandom was small and I wanted to help contribute. Nowadays, the fandom as gotten really wank-y and the actual art and fics (when the tumblr tags aren't full of people spamming/whining about the spamming like this is their first controversial ship) has gravitated towards things I dislike/am uncomfortable with, like daddy kink, omegaverse, and various bad AUs. I don't dislike this ship, but I don't have the passion for it like I used to.