To be fair to Bruce, he was subtle. It was, in fact, a testimony to how very subtle he could be that it took two weeks for anyone to realize that none of them had touched him since... Since. The Avengers were a very tactile group of people, all things considered, and the way he managed to effectively avoid even the most superficial brush of fingers without notice attested to how illusive he could be.
That having been said, no man can avoid basic contact with the people he's living with without someone figuring it out. Unfortunately for Bruce's sanity, Tony was once again the one to figure it out.
They were having a very Avengers breakfast, with Steve making poor attempts at what could charitably be called cooking, and Thor hogging all the poptarts, and Natasha texting, and a hungover Tony mainlining coffee, and Clint stumbling in and preparing to cling to the nearest back: namely, Bruce's.
Bruce sidestepped him with careful, but laughing eyes and no one said anything as Clint simply staggered over to Thor and began to make puppy-dog eyes at his sugary breakfast.
Unbeknown to Bruce, Tony watched, and he started to see how when the older man passed the salt he did so in a way that insured that no one's fingers ever brushed his, or how carefully he skirted around the kitchen. It could be a coincidence, but he knew better. So, when Bruce left for his lab Tony took a pull of whiskey (to the chorus of Jesus, Tony, really? from Steve) for courage and followed him down.
That particular conversation was put off by alarms and a confusing call about Loki and a six-legged horse from a young, harried SHIELD agent.
No one was very fond of that paticular mission, and the less said about it the better.
The real conversation happened in medical, after the mission we do not speak of, with Tony hovering, all stiff bravado and self-depriciation, next to the industrial strength bed where Bruce woke up.
For once Tony was grateful for that Sorry About the Sexual Harassment speech Pepper had made him memorize a lifetime before.
Bruce listened for the first couple minutes disoriented and convinced he was having a particularly odd dream, because in what universe was Tony the problem? Still dazed, he sat up and outlined his actual reasons, because, like he did with all their more crazy ideas, he followed Tony's lead; if he was prepared to talk, then so was Bruce.
He really should have been more suspicious about how carefully Tony listened to his careful No Touching Unless Necessary plan and the reasons behind it, but he wasn't firing on all cylinders yet. As it was, it took him by surprise when Tony ducked down and gave him a quick peck on he lips, before heading out the door with only the quick call of "Immersion therapy!" over his shoulder.
For a few tense moments Bruce waited for the Other Guy to appear, because at least it was in SHIELD, where the people around them stood a chance of surviving, but the moment never came, and suddenly he was reminded of that second touch.
Rusty and startled laughter floated down the halls.
Things almost went back to normal.
Almost. Because now Tony kissed him with quick, dry, presses of lips every time he had a scientific breakthrough, or picked a good movie on movie night, or woke Tony up so he wouldn't sleep in his lab again. The only people who seemed surprised of this new developement were Steve (for reasons that should be obvious) and Bruce himself, who kept waiting for Tony to realize he might never be ready for more and move on. He couldn't understand why he stayed, but he knew of one person who would.
Bruce didn't even have to say anything. Pepper took one look at him and steered him into an empty office. She sighed, and called for some tea and Tony's file. She had a meeting, but the file would answer all the questions she would be both able and willing to. He didn't think he could ever fully forgive her for breaking Tony's heart, but in that moment he came close.
For the next few hours he sipped his cooling tea and read the story of the man he knew, told through a lense of both exasperation and fondness that he empathized with immediately.
The file called Tony self-destructive, yes, but it also called him selfless. It called him stubborn and funny and all sorts of things Bruce knew within seconds of meeting him, and a few things he'd learned since then. He closed the folder quietly and left both it and his thanks with Pepper's secretary.
There was something he needed to do.