Story Title:The Y Intercept
Rated: R for sexual situations and the general abuse of science
Status: Complete // 500+
Summary: [Spanner/Shouichi] In which Spanner can't turn his geek off.
Steve's Notes: Written for questofdreams' Happy New Year: Porn Post. I should really be doing other things like writing for the sn_exchange. D:
Disclaimer: Katekyou Hitman Reborn! © Amano Akira

Spanner knows, in a universe of infinite possibilities, that it would be illogical to label any occurrence impossible. He also knows that it would be illogical to say "This isn't happening" because, while highly improbable—about 7,624,395 to 1—denying that this was happening was like denying that the maximum speed of any mass in the universe was the speed of light.

And by "this", of course, Spanner means the way Shouichi rides him like he's the y to Spanner's mx+b.

"Spanner," Shouichi gasps as he rises and falls and rises again like a complete sine, thighs trembling, rocking at the brutal speed of v with a demanding frequency of ƒ—which means, Spanner thinks in the back of his brain as he thrusts upwards at the crest of Shouichi's negative troughs, λ equals sex on scuffed linoleum floor of their private lab.

It started out innocuously enough, like when barium hydroxide octahydrate crystals and dry ammonium chloride were introduced in a Büchner funnel; nothing happened until Shouichi's hand brushed his hand and lingered, the blue-white heat that combusted in his gut bringing them together. Soon Shouichi's shoes were forgotten underneath the emergency shower, his soft cotton shirt and hoodie by the fume hood, his cargo pants and spaceship boxers by the rack of Bunsen burners. He's completely naked save for his argyle socks, one tight against his calf, the other clinging stubbornly to the arch of his foot. Spanner, by contrast, is completely clothed, only the placket of his jeans open and bunched atop his straining thighs.

"Oh," Shouichi mewls above him. His pink blush has spread from his cheeks to the tips of his ears, down his throat to his pale narrow chest; clumps of his wild red hair stick to his sweaty forehead and curl obscenely against his neck. He alternately bites and sucks on his lower lip while his fists hover just above his head, as though the hands Spanner has seen disassemble intricate machinery with ease are sweetly unsure. "Oh, oh—!"

It is, Spanner thinks, the single most satisfying experiment of his life. Shouichi is more unpredictable than any chemical reaction, more responsive than any simulation, more complex than the wires and code of a computer. If he tilts his hips just so, Shouichi might whimper or his eyes might snap open; if he pinches Shouichi's rosy nipples to hard buds or scratches him with his nail, Shouichi might choke on a sob or hiss through his white teeth; if he thumbs Shouichi's straining cockhead with his still gloved hand, Shouichi might falter or he might come.

Inevitably, Spanner knows, there is only one outcome. But there are so many variables in the realm of when, where, and how that, even when Shouichi doubles over, the patella caps of his legs touching the paired temporal bones of his skull, his mouth slack and hands tight in his hair, Spanner is surprised by his vicious need to know every single one, no matter how many times or how many years it takes.

"For the sake of science, of course," he tells Shouichi once the reactants have formed a final product, and they've cleaned the mess away.

"Of course," Shouichi replies with crisp, eager understanding, and Spanner is glad he's found someone who understands.