A/N: Hey guys! I'm just posting my last few prompt fills from the summer; now that the school year is over, I'm not taking any more. Thank you all so much for the support while I wrote all of these!

The prompt was: "could you do something with brucenat making out in the lab? (sorry if it's too vague - i'm just a perv that wants the baes getting it on in there)"

Enjoy!

Helen was not accustomed to outright displays of either emotion or affection. Either one often engendered disapproval from her peers, and while Helen wasn't above swearing up a storm in her mind when one of her colleagues' pigheadedness got out of hand, she usually kept to restrained smiles and straight-to-the-point statements.

Not that she couldn't appreciate Stark's whirlwind personality, or the enthusiasm of some of her students. It did make for a refreshing day when Stark video-called her with a new idea, ranting for about an hour before he would abruptly end it. Once she became acquainted with the Avengers, however, Bruce Banner especially, it was something of a relief to occasionally be around someone who, like her, refrained from being very expressive.

Today was the third day of one of her many business trips to Avengers Tower, where she had been called to consult with Dr. Banner on the possibility of synthesizing her tissue regeneration technology into a drug that could be used in the field. The third wheel to this scientific collaboration was, apparently, former Agent Romanoff, who had volunteered to be the test subject.

Helen hadn't thought much of it at the time; Romanoff, like herself, was a practical woman who strove for her goals - in this case, furthering the capabilities of the Avengers in the field. In fact, there had been so little inflection in her voice when she had agreed to it that Helen would have thought that Romanoff saw it as little more than a chore. Now, however, she paused outside the door to the lab; the light was on indicating that it was already occupied.

Helen frowned. She'd made sure to arrive early in order to set up her equipment.

"JARVIS," she said. "Could you tell me who is occupying the lab?"

"Miss Romanoff and Dr. Banner are inside. Shall I inform them of your arrival, Dr. Cho?"

"Please do."

There was a moment's pause, during which JARVIS was most likely relaying her message, before the door slid open.

Helen greeted both quickly and without inflection, having eyes only for her equipment. Her observational skills, however, prevented her from focusing completely on setting up. Dr. Banner was (not very discreetly) facing away from her, and Romanoff looked just a tad too smug for someone who had been merely conversing with the other occupant in the room. There was also the mussed hair, the flushed skin…

Helen shook herself. Their private lives were hardly any of her business, though it certainly explained why Romanoff seemed to live as Dr. Banner's shadow for much of the time. And why Dr. Banner seemed to relax when she was around. And why Romanoff volunteered for this test run…

It was odd, considering two of her most reserved colleagues being the ones to make out in one of the labs. Helen almost snickered at the thought, and covered it with a cough.

Romanoff moved to stand next to her, though not before she brushed her hand over Dr. Banner's. Reserved, maybe. Subtle? Hardly.

Helen pushed the thought out of her mind. It was time she got to work.

"How are you feeling?"

Natasha grimaced. "Kind of tingly. Like there are gnats crawling under my skin. Not painful, but not super pleasant."

Bruce looked cautiously optimistic. "Well, as long as it doesn't get any worse."

"I have faith in the power of science." Natasha kissed Bruce on the cheek. "I'd resume our earlier activities, but I'd prefer we do those when my skin isn't actively trying to knit itself back together."

"Good plan," Bruce agreed. That wasn't enough to stop him from kissing her back, on the lips this time. Natasha responded languidly, reaching up to tangle her fingers in his hair. They broke away before it could get too out of hand.

"Don't worry," Bruce said. "I'll keep you company. In case you, y'know, explode or something."

"Thanks," Natasha drawled. "Really comforting."

"I thought you had faith in the power of science?"

Natasha rolled her eyes. For the moment, however, she didn't mind being Dr. Cho's guinea pig. Especially not if it meant that she got to spend some time with Bruce.