Just the light glinting off the edge of the scalpel's blade sent shivers down Bruce's spine, shivers he didn't quite feel but knew in the play of muscle against the cold table. He licked his lips, watching as Tony stepped forward, body rippling beneath the tight black and blue under-suit modified to absorb radiation. Bruce's eyes caught on the sharp line of a hip bone, rolling so perfectly within its joint, working seamlessly with Tony's spine to make his gait a thing of wonder.
Tony stopped beside the lab table, brushing the heel of his hand over Bruce's shoulder as he moved to drag his fingertips over the dotted lines forming an uppercase “Y” on his torso, ending just above his belly button -which, Tony thought absently, was much too adorable to be normal.
“Feel that?” he pressed down hard. A shake of the head. He dug a nail in. Another shake, this one with an indecisive little frown.
“Want more?” Bruce saw Tony's eyes flick over to the table and the prepped syringe on the metal tray beside a multitude of scalpels, a balisong -they were going to have a talk later about proper tools when Bruce could focus again- and forceps with colorful rubber bands already loose around them.
Tony stared him down for another few moments before relaxing his shoulders with a nod, tugging the mask over his nose and mouth and bringing the scalpel to the left branch of the “Y.” Bruce took in a deep breath and as he let it flow back out, Tony pushed down and dragged, tilting his hand at the last second to continue down the stem. He paused, watching the blood run from the cuts to pool in the hollow of Bruce's throat and drip from his shoulders onto the table. He bit the inside of his cheek and moved quickly to make the last incision, setting the bloody tool aside.
With a twitch of his fingers Tony called up a holo-screen. Bruce watched the program they'd written just days before start up and begin scanning in his peripheral vision, eyes following Tony as the man grabbed the forceps, gently pressing them on either side of the flaps of skin, tightening the rubber bands and pulling them back to open him to the sterilized lab air.
Bruce watched an almost tentative gloved finger press at his sternum, dragging through the blood to reveal the stark white of the bone before moving off to the side, pushing against the cartilage connecting it to his ribs. Tony's tongue darted out to run over his bottom lip and Bruce ground his teeth to muffle his moan.
Tony looked awed, splaying his fingers wide over Bruce's ribs and pressing lightly with his entire hand to feel his lungs expand, watching his diaphragm move his liver lightly up and down. He trailed down to the slick bulge of his stomach, cupping it in his palm, closing his eyes to focus on the heat through the thin glove. When he opened them again, he looked up to find Bruce's eyes locked on his, cheeks flushed a soft pink, bottom lip bitten red.
He grinned, rubbing along the edge of a rib to gather a drop of blood and smear it between his thumb and index finger. Bruce felt a faint coil of arousal and wondered if Tony could see it inside him, a pressurized ball of heat that, under the effect of the numbing agent he'd been injected with, felt more like the tingling sensation of being touched after standing out in the cold.
Tony wanted to keep playing and Bruce very, very much wanted the same -wanted to watch Tony cut through the cartilage holding his ribs to his sternum and crack his ribcage apart, open him up completely, push rough against his lungs to hinder his breathing, curl his fingers beneath and around his heart and feel it beat, speed up and up and up- but they couldn't, had to stop before Bruce lost enough blood to force the Hulk out and into a rage.
Bruce didn't answer, just took a deep breath that pulled a groan from deep in Tony's chest and spread his mind thin like a spiderweb, letting Hulk seep forward to fill in the gaps. He wanted to watch Tony but couldn't not look into his own body, watch the blood run slower and greener, bones going minty and growing. He reached to remove the forceps himself, knowing Tony couldn't be trusted to do much of anything at that point.
And just the sight of Bruce's fingers brushing over his own muscle and bone and and and-
Tony couldn't think, could hardly breathe as he collapsed against the table and palmed himself through his hazmat suit, ducking his head to watch Bruce's skin go green and seal up before flushing pink again, the gorgeous thing he'd been inside just moments before -oh god oh god- whole once more and Tony wanted desperately to lick the faint silver scars. He went to do just that but Bruce pushed himself up and forward, pulling his mask down to bite into his mouth and griping his face with bloodied fingers.
“Next time, I want to feel it all, want you to touch my heart, god Tony I want you so mu-”
And Tony lost himself.