Bruce likes to consider him a man with exceptional self control. His entire being relies upon it, after all. The skill with which he steps on the errant dimensions of his personality is unrivaled. So, he has to wonder how Tony Stark pierces straight to his bones, slipping past all those defenses Bruce has so carefully placed.

It's late; one in the morning just gone. Tony is hunched over a digital replica of the suit gauntlet that JARVIS has recreated. A look of deep concentration pressed into his features, Tony pulls back the anterior plating to bare the wiring beneath. Two of the circuits are quickly rerouted, and another is deleted entirely. An error code pops up in midair beside the gauntlet. Bruce watches as Tony huffs and rewrites the coding. Four separate redundancies are taken out before Stark finally moves back to the gauntlet. Another circuit is replaced and re-coded.

Bruce is enraptured by it. Watching him work is relaxing; almost as relaxing as doing the job himself. Tony understands every little number in the code he writes. He knows exactly what needs to go where. The man is a genius, and it's strange that even though he's so damn cocky about it, people still manage to forget how smart Tony Stark really is. They forget that there's a reason he's rich, and a reason he's so egotistical.

There are times Banner feels like a kindergartener when he's faced with the true extent of Tony's mind. But Tony never treats him as anything less than an equal. They speak the same language, and more often than not their conversations dissolve into something Clint likes to - cheerily - call, 'science bullshit.'

They're on the same level, even if sometimes Bruce doesn't feel like it. Tony leaves him coughing in the dust and then has the decency to act like they've crossed the finish line side by side.

It's one of the things that makes Bruce admire him. One of the many things, stuck in there somewhere between Tony's absolute genius and his snark. And, just maybe, there's room in there for the look he gets when he's so deeply in thought that the room around him doesn't even exist.

You are so fucked, Bruce thinks to himself.

Grumbling under his breath, Tony expands the digital form of the gauntlet and then slips on the physical prototype. It flexes perfectly around his hand, and Bruce admires the technology as it comes to life.

"JARVIS, copy the code to the second gauntlet. Run a preliminary diagnostic on both and check for software redundancies."

The diagnostic starts up before their eyes. JARVIS, a smile in his voice, says, "Will that be all, sir?"

"Run the targeting systems on the Mark 8 through a simulation."

Finally, Tony turns and eyes Bruce. He tries to make it look as though he's been working on the computer, but is mostly certain he's failed, if the ghost of a smirk on Tony's face is anything to go by. The taller man stands, approaches him, and grins. "I am starving."

"Yeah, well, you're always starving," Bruce tells him, smiling broadly to match Tony's grin. "Did you fix the weapons deployment system?"

A flicker of something unreadable ignites in Tony's face; a foreign element that alters his expression. Suddenly, he's looking at Bruce as though he is a puzzle waiting to be solved. Tony's fingers twitch. Bruce catches a breath and, unconsciously, holds it. Then Tony is falling back, smiling as his mask slips back into place. "Easy. The circuit was wired wrong. Child's play."

Bruce frowns, but lets it go. If Tony wanted him to know what that mask obscured, he would tell him.

Abruptly, Stark turns to the computer and leans in to see what Bruce has been working on. Alternate power converter for the new Stark Tower. In order to prolong the life of the prototype, they would need something new. Tony had worked out the initial blueprints, and then handed them over willingly for a second opinion.

Now he sucks on his lower lip, taking in the changes that Bruce has made. All the while he is leaning over Bruce's shoulder. It confuses Bruce even further, because normally having someone in this proximity would drive the Other Guy mad. But things are different when it's Tony. He's a variable that changes the outcome of the experiment. Things that the Other Guy would never allow (like someone entering his personal space) slip past without issue when that someone is Tony Stark. As though he calms the beast.

No. It's not the beast that Bruce's self control fails to rein in. It's that wayward need that consumes him. It's the smell of Tony; a mixture of heated metal and expensive cologne, that sits hot on his tongue. It's the heat off the other man's chest as it presses to his shoulder. The computer screen blurs into a mess of numbers and diagrams, and Bruce struggles to control his breathing.

"JARVIS," Tony says, startling Bruce from his thoughts, "Run a simulation over the new parameters Bruce has given us."

"At once, sir," the AI replies.

Then Tony's looking down at him, and the smaller man is still playing over hearing his name fall from Tony's lips. And he's stuck on that part, and stuck on how the light catches the billionaire's eyes.

He catches Tony utterly by surprise. One second they're looking at each other and the next Bruce is crowding him against the desk and kissing him. Tony's every muscle tenses beneath the contact, and he stands catatonic. Then the spell breaks, and Bruce lurches back, cursing darkly.

Certainly, Bruce hadn't expected reciprocation. How could he expect an effect when he hadn't even planned the cause? No, this was only to be expected. Shaking his head, he recoils from Tony.

Green seeps into his skin. The Other Guy shouts inside his head, forcing himself from the caged walls of Bruce's mind. But then Tony is talking, one hand pressed to Bruce's heart. He recites useless code, and parameters, and talks science that Bruce is too far gone to understand. The Other Guy stops. The Hulk falls silent, listening to Tony's voice. Rapt.

The green hue begins to recede. The screaming in his head stays away.

A hand slips around his wrist. And he's trying to figure out what it means, what any of it means, but then Tony is on him. Heated lips find his and teeth graze his skin. A spark dances across his tongue. They make it to the wall, and no further, before a hand is loosening his belt.

Tony pushes his hand down Bruce's pants, wraps a hand firmly around him and strokes from base to tip. Bruce all but comes apart underneath him, his legs going weak. He's crowded, swiftly, closer to the wall, and Tony's body holds him upright.

When he comes - embarrassingly soon - it's to Tony's teeth on his throat. Tony's grip on his dick.