A/N: Hey! I answered a few prompts on Tumblr regarding this pairing. Figured I might as well post them here.

Probably set somewhere between CA:TWS and Age of Ultron. Enjoy!

The thing is, he's… not usually one to come down here.

Bruce likes to call himself a pacifist. Well, as much of a pacifist as a guy who turns into a giant green rage monster and smashes things can be. He avoids fights where he can, tries to break them up when he can't. The latter is usually only when Tony and Steve get into an argument, and when that happens, he tries to slink out of the room. It's better to let Pepper handle those.

Hence, he rarely finds himself down in the training room, even though the others frequent it. Everyone else on the team has brought it up with him - that he should get some form of hand-to-hand training, so that he doesn't have to bring out the Other Guy if he's in immediate danger - and he's either politely declined or deflected away from the subject. Sure, he'd attempted to learn Aikido while he was in Brazil, but… well. Avoiding fights altogether works better.

So how he's found himself in the training room at two in the morning is a mystery to him. He thinks it might've had something to do with Tony shoving him out of the lab and telling him to either get some sleep or, "Go get Cap out of the training room, he's been down there for three hours and even I'm feeling pathetic on his behalf."

The latter must've been the one that registered in Bruce's brain.

Except that it's not only Steve who's down here. Which… means that Bruce should turn around and go back to the lab or go to bed (ha, yeah, that'll happen), but he stays in the doorway, oddly transfixed.

Steve is pitted against Natasha, who (in spite of the disadvantage in strength) is an even match. She's much more accustomed to fighting opponents that are larger than her, and she uses her agility to force Steve off-balance time and again. The match ends with her pinning Steve to the ground, one knee in his back.

"Yield," he pants, but he's grinning when she helps him up.

"Thanks for the bout, Rogers," she says, moving off to grab a towel from the edge of the boxing ring. "Maybe next time you'll actually stand a chance."

Steve laughs. "That's how it's gonna be, huh?"

"Do I even need to answer that?" Natasha turns around to shoot an expectant look at Bruce. "Here to get in the ring, Bruce?"

Steve blinks in surprise - unlike Natasha, who notices everything, he hadn't seen Bruce enter - before he bids them both a good night and exits. Suddenly conscious that he's alone with Natasha Romanoff (and is trying very hard not to notice that she's in a sports bra and yoga pants because no, he is not going to go there), he twists his hands together.

"Um…" She lifts an eyebrow. "I think I was supposed to get Steve out of here, so… I'll just head back to the lab."

He turns around and is about to march out the door.

"Bruce."

Something about the way she says his name makes him pause. He looks back at her. She hops over the edge of the boxing ring, hanging her towel from her shoulders. Natasha has never been one to beat around the bush, but he gets the sense that she feels as awkward as he does, in this instance.

Then she smiles.

"Not even going to say hi?"

That's enough to startle a laugh out of him. "Hi, Natasha."

"I was just about finished, too," she says. "You want to head upstairs and make smoothies? If I'm right, you haven't eaten anything besides granola bars in the last eight hours."

Bruce blinks, then goes over the last eight hours… all of which were spent in the lab, occasionally grabbing a snack while he was working. Well. He was probably still doing better than Tony, at any rate.

"Sure," he answers. Why not?

The two of them make their way out of the training room. On their way up to the communal kitchen, Natasha's hand settles on his lower back, its presence warm through his flannel.

He kind of wishes he minded more.

Natasha isn't usually one to come up here.

In all honesty, she's bored out of her mind. Clint is playing on the Wii and yelling at the TV (again), Tony is in his workshop trying to work himself into exhaustion (thank god Pepper is coming back to the tower today), Steve and Sam are off looking for Barnes (she didn't have the heart to tell them that this would probably be as fruitless of a lead as the last one), and Thor is off-planet (though that's been happening less often). So she's going up to the lab, because she has a bit of an absurd need to not be alone right now.

Bruce doesn't notice her enter. He probably wouldn't notice if she danced in naked (and wow, why is that the example her mind sets?), because he looks like he's fallen asleep on the counter. None of them have great sleep schedules - some because they don't need as much, and others because sleeping isn't desirable - but Bruce and Tony are probably worse than the others. Bruce, at the very least, eats food other than pizza.

Natasha suddenly feels like she should've made some tea, or something. He could probably use it. As it turns out, he does have an electric kettle sitting in the corner, and some boxes of chamomile shoved behind a stray bit of paperwork, so she putters around making mugs for both herself and him. She deliberately clinks the mugs louder than normal, so that by the time the bags are soaking in hot water he's blinking blearily at her.

"Hey," he says groggily. "Thought you were down with Clint."

"I can only take about five minutes of him verbally abusing his Smash character of choice."

Bruce chuckles, then nods at the tea. "Chamomile."

"Yeah." Natasha removes the bags. "You usually put honey in yours, right?"

"Uh-huh." He looks momentarily surprised that she knows that, before the look is replaced by wry acceptance because of course she knows that. Natasha doesn't know everything (as she told Rogers), but she does know a lot more than most.

Natasha hands him his mug before settling on a stool next to him, cradling her own in her hands. They sit in silence for a while, each taking cautious sips. Natasha's pretty sure that she burns her tongue on it, but she doesn't mind.

It's… not awkward. It should be, but it isn't.

"Are you alright?" Bruce asks her. He's always been more perceptive than she'd like.

"Not sure," she answers honestly. She doesn't say anything more, but Bruce nods like it's a perfectly acceptable answer. She wishes it was, and wishes there was a way for her to put her feeling in words.

"I think I'm gonna head to bed," he mumbles, once he's finished his tea. He squints at her. "That wasn't your goal with this, was it? Because chamomile always puts me to sleep."

Natasha hadn't known that, but she smirks at him anyway. He rolls his eyes.

"Hey," she says, her mind suddenly blanking. "Do you want to go out to dinner sometime?"

He stops moving and looks at her, very carefully. He's probably putting two and two together now - her actions towards him the other night, when she'd been… a little forward with her physical contact. Her not-so-subtle attempts to make sure that he ate properly. Her repeated offers for sparring lessons.

Natasha's face gives no hint at the internal panic attack she's suddenly having.

"Sure," he answers at last. "Is, um… is it going to have any meaning?"

Relief floods her.

"I was kind of thinking we should wait and see," she admits. "That okay?"

"That's fine." He smiles. "Tomorrow at seven?"

She stands and moves into his personal space - slowly, so that he has the chance to back out, if he wants. It's just so that she can kiss his cheek, but she lingers for a moment, allowing herself a small smile.

"Tomorrow," she breathes quietly in his ear. Then she slips away, leaving that promise behind.