Disclaimer: not mine.

Summary: Bruce finds himself the subject of one of Tony's experiments. He also finds that he doesn't mind. Science bromance with brief appearances by the team and maternal!Pepper.

Touch Therapy

"Do you like it when I touch you?"

A normal human being may have reacted with flirtation, or possibly dismay. Bruce raised his eyes to Tony and gave a slow blink. He was, in fact, proud of himself for reacting with as little awkwardness as he did.

"Does that need clarification?" Tony grinned, and Bruce nodded once.

"Does your heartrate lower significantly at physical contact with another human, and does this lower heartrate subsequently make it easier for you to control certain slightly negative tendencies? Such as, say, the tendencies to turn green and splinter solid steel?"

Bruce blinks. Tony clarifies further.

"I've been having JARVIS monitor your heartrate- ess-oh-pee, you understand- and I noted one pretty prolonged decrease yesterday while we were working in the lab." He calls up some info readouts on a screen; in typical Tony fashion, he hasn't even given Bruce time to get annoyed before diverting his focus elsewhere. Displayed on the screen is a line with the initial BB and a tiny heart next to it.

The line is wavy but holds mostly steady, though high above the normal rate indicated by a paler mark. The time of day is plotted, and at about 2:35pm there is a sharp decrease that lasts nearly four minutes and takes almost an hour to fully recover from.

A video pops up in a window below the line. It's security footage, and Bruce watches himself staring raptly at a diagram on the table.

The timestamp speeds along, until at 2:34:49, Bruce calls Tony over to look at his work. Bruce remembers that rather inconsequential moment, and now that he's got a schema for it, he remembers what happened next. His memory is confirmed as, on the video, Tony comes to stand beside him, leaning in for a better look. Casually, he braces a hand on Bruce's shoulder as he does so.

Bruce- Bruce of this moment- feels his eyebrow lift as he watches the monitor; the heartrate graph zooms in on the appropriate segment. It dips as Tony talks, and when he finally takes his hand away it slowly begins to rise again.

Tony- Tony of this moment- is grinning smugly, bur Bruce can't take his eyes off the screen. He's searched for correlation between his urges and dozens of variables already- everything from ambient noise to calorie intake to the weather. But he's never thought of touch.

"You have no idea," Tony crows, "how happy it makes me to say... we have a new experiment to run."

The first day's results are promising. Tony stands close as they study the read-outs together.

Hand on shoulder, 10 seconds

trial 1: -6%, trial 2: -8%, trial 3: -5%, trial 4: -5%, trial 5: -9%

Hand on shoulder, 30 seconds

trial 1: -10%, trial 2: -13%, trial 3: -16%, trial 4: -14%, trial 5: -9%

Hand on arm, 10 seconds

trial 1: -7%, trial 2: -5%, trial 3: -12%, trial 4: -4%, trial 5: -6%

Hand on arm, 30 seconds

trial 1: -21%, trial 2: -17%, trial 3: -15%, trial 4: -12%, trial 5: -18%

Hand on knee, 10 seconds

trial 1: -2%, trial 2: -5%, trial 3: -3%, trial 4: -3%, trial 5: -6%

Hand on knee, 30 seconds

trial 1: -9%, trial 2: -13%, trial 3: -7%, trial 4: -10%, trial 5: -11%

Tony points to trial 1 of experiment 4 with an awkwardly genuine grin. "That's almost a normal heartrate there, Banner. Just from me putting my hand on your arm for half a minute. I shouldn't let that go to my head, right?

"I've had this hypothesis for a while," he continues, and suddenly Bruce thinks back to all the unnecessary touches he's received since coming to stay at Stark Tower. Maybe he should be pissed for being the subject of an undercover experiment. Instead all he can think of is how the man standing in front of him isn't afraid to piss him off, isn't afraid to slap him on the back or bump shoulders with him in the hall.

"We need to up the ante," Bruce says. Tony just smiles.

"JARVIS, record," Tony monologues, and Bruce is pretty sure it's for comic effect because when is JARVIS ever not recording everything? "Trial one of Jolly Green Wrangling is a go. Ten seconds on the clock."

"Jolly Green Wrangling?" Bruce chokes- they never agreed on that one- but the only reply he gets is Tony's arms sliding around his waist and squeezing.

An hour later, Bruce's heartrate isn't rising between trials anymore. They agree that it's best to take a break until morning.

The figures are promising; they're up to a minute now and they've actually gotten Bruce's heartrate to dip below average.

Standing in the middle of the lab, surrounded in a secure circle of Stark arms, Bruce is feeling pretty good about the experiment. Sometimes so good, he forgets it's supposed to be one.

He blows a slow stream of air out of his nose- not quite a sigh, but more than an exhalation- and sinks deeper into Tony's embrace. He closes his eyes and buries his face in the crook of Tony's neck. The arc reactor presses against Bruce's chest, but not uncomfortably.

"You're shaking," Tony observes; his voice is still toneless, frank, but there is little less volume to it.

"Note it, JARVIS," Bruce replies, trying to stay neutral. His knees knock; he feels like a car running on fumes, but that's an absolutely amazing feeling. Forget meditation, forget deep breathing. Forget weed. This is the least keyed-up he's been in years.

Tony hasn't filled him in on the future plans; they've agreed that foreknowledge is just an additional, unnecessary variable. But Bruce has a pretty good idea what the next step is when Steve shows up the next day.

Steve looks perplexed, and maybe just a little pissed. He pulls his phone out and reads the message displayed there in a haltingly mechanical voice. "Captain. Stop. Need you to come and hug Banner. Stop. For science... stop. For science is in all capital letters." He slides the phone back into his pocket and flashes his waiting-for-an-explanation face.

"I don't see what you don't understand about that." Tony's voice is calm and sweet.

Steve looks like he's about to argue, but he stops when he catches sight of Bruce's face. Sighing slightly, he approaches.

Tony has made it clear: at this moment, the data collection is on him. All Bruce is supposed to do is stand there and be embraced.

Hugging Steve isn't like hugging Tony- for one thing, Steve is tall and broad and Tony is actually pretty small and has a plate of metal in the middle of his chest. Tony also hugs kind of casual and slow, like there's all the time in the world. Steve seems to favor grabbing Bruce tightly, unyieldingly, like at any minute he's going to have to throw him to the ground and shield him from something awful.

Bruce doesn't think he's ever understood Steve so well.

"I really don't understand why he reads his text messages like telegrams," Bruce comments, fishing for anything to say once Steve has left. "I'm not big on history, but it doesn't seem accurate." It wasn't the kind of comment that required a response, but Tony laughs. He takes his phone out and pulls up a screen before handing it to Bruce, who reads:

captain. stop. need you to come and hug banner. stop. FOR SCIENCE. stop.

Bruce bursts out laughing. Because they're trying to only make contact during trials now- to keep their data clean- he has to fight the sudden desire to throw his arms around Tony.

Clint hugs him with a smirk and an overt friendliness that soon gives way to something shy and almost gentle. Thor hugs him like it's a precursor to an Asguardian wrestling match. Natasha hugs him while wearing a tight black tank top, and Tony giggles obnoxiously while that particular trial fails to result in any decrease in heart rate whatsoever.

Pepper is their last volunteer. It's late at night when she arrives, looking tired, but cheery as always. Bruce pushes himself to his feet as she enters and smiles her good-natured smile. It's the smile of a woman dating a man like Tony Stark, a man who spends more time with his lab buddy than her some weeks, a man who has just asked her to visit said lab and embrace said buddy for a legitimate experiment.

"Pepper!" Tony, childishly delighted by her presence as always, pulls her aside to show her the data so far. She nods indulgently as he whispers things to her that Bruce can't hear. Finally, she turns.

"Bruce?" Pepper's head is slightly cocked, and Bruce nods his assent, stepping towards her. Her arms are thin but strong as they close around him, and he clutches her to his chest just as tightly.

The first thing Bruce thinks is, Pepper smells like angel food cake.

The second thing Bruce thinks is, so this is what it feels like to be held.

The third thing Bruce thinks is, if she and Tony don't want to have kids, the world is missing out on the greatest mother ever.

"Okay there, buddy," Tony breaks in, laughing a little awkwardly, but Pepper shoos him away with one hand, turning a bit so Bruce's face- along with the tears sneaking their way down it- is hidden from Tony.

"Let me enjoy this," she sulks. "You never hug me like this."

"Maybe I should start," Tony muses, as Bruce sends silent thanks to Pepper's impeccable discretion, and tilts his head down so that the wetness on his cheeks is dried by her blouse.

"You're only supposed to hug him for ten seconds at a time," Tony insists, little-boy annoyance seeping into his voice.

"This isn't science," Pepper replies patiently, her long fingers beginning to trace loping shapes on Bruce's back. He melts against her, soothed, exhausted. "This is our friend."

That night, Bruce doesn't just sleep better than he has post-Hulk. He sleeps better than he can ever remember sleeping before.

The next day Tony is quieter than usual, nearly contemplative, stilled. Rather than greeting Bruce with a run-down of the previous day's data, he smiles as Bruce enters, and says nothing as Bruce goes to one of the screens and begins to check his email.

Halfway through an obnoxious forward from Steve that he feels compelled to finish, Bruce is interrupted by the snug clench of Tony's arms.

"What are you doing?" It's not a squeak, not really, but it's certainly not his normal voice.

"Hugging you," Tony replies, and tightens his grip.

"I can see that. But what are the parameters?" Despite his token protests, Bruce can feel himself relaxing; instinctively- he has instincts for this sort of thing now?- he wraps his arms around Tony's waist.

"Your heartrate decreased in the trial with Pepper more than it has in any of ours. That doesn't make sense to me. I'm your number one pal. She's just your number one pal's lady pal." There's an odd weight on Bruce's shoulder as Tony's head comes to rest there. "So, if she wasn't the key variable, I thought, what else was different about that trial?"

Bruce inhales slowly. "It wasn't a trial," he replies; Tony's hair moves softly against his cheek as Tony nods.

"Voila."

"So we just spent a week deciding that basically, I like hugs."

"We spent a week using science to make you admit it," Tony shoots back, and they laugh, still holding on tight.