A/N: Thank you all so much for your positive response to chapter one! Your kind words definitely inspired me as I worked on chapter two all week. I hope you have as much fun reading it as I did writing it…and that you'll let me know. ;) Chapter three's well under way, so I should have another update next week. I'll try to stick with a Sunday posting schedule as much as possible. As usual, many thanks to my awesome beta reader, malintzin, who helps me sound like I know what I'm talking about in the MCU.

2. Third Wheels

For two years Bruce had been living in Avengers Tower with Tony, and his cheekbones still prickled with a flush whenever Pepper Potts came to town and greeted him with a hug. Which, he had a sneaking suspicion, was partly why she always greeted him affectionately, if her eyes, twinkling with mischief as she drew back, were any indication. That, and because Tony was equally reliable in his reaction, scowling and sulking when his girlfriend withdrew from his attempts at a welcome back makeout session to greet his lab partner. It was like being back in high school, really, which was not a period of his life Bruce had ever thought he'd want to re-live. Funny, how with age and experience came perspective.

And state-of-the-art lab equipment.

The usual small-talk followed:

"How's California?"

"Sunny," she replied. "You should come sometime. I worry you're getting a vitamin D deficiency holed up in this lab. Not that I don't appreciate you keeping Tony out of trouble."

"Wait, is that why Banner's here? I thought it was so I could get him into trouble."

"Unfortunately," Bruce said, "that's slightly more accurate."

Today, though, the conversation took a new turn.

"One more reason I'm glad Agent Romanoff's staying here now," said Pepper. "You two mad scientists need supervision."

"Uh, excuse me," said Tony, "we happen to be two very happy scientists. Especially me," he added, slipping his arms around Pepper's waist. "Or I will be, if you make out with me."

Pepper pecked him on the lips, then continued with the conversation, "Is she all settled in?"

"Who?" Tony asked.

"Natasha."

"Are you accusing us of having a girl in the house? Because I swear to God, you're the only woman in the world to me. I pine for you, night and day…"

Rolling her eyes, Pepper turned to Bruce, eyebrows raised in expectation.

"I think what Tony's trying to say is that we don't see a lot of Natasha."

"No, I really am trying to say that I pine for you, Pepper."

"Okay," Bruce said, "he does do that."

Although he wouldn't necessarily define it as pining so much as moaning about how much long distance relationships sucked.

Once, not in the mood to play Love Doctor, Bruce pointed out that that long distance relationships sucked more for people who didn't have private jets and flying suits.

Tony replied, "That's one of the things I love most about you, Bruce. You're such a good listener."

"If by listener you mean captive audience."

"You really get people."

Pepper got people, too-if Tony really qualified as people-so when she grinned conspiratorially at Bruce he thought it wouldn't come at all as a surprise to her what played out in her absences from New York. But she told Tony his sentiment was deeply touching and let him kiss her again, more lingeringly this time.

The dynamic between the three of them wasn't so much like high school that Bruce was embarrassed by their PDA-although it occurred to him maybe that wasn't a term to apply to adult relationships. He turned back to the simulations he'd left running, to give them their moment, but not before he felt a twinge in his chest as his traitor mind inevitably thought of how long it had been since he had one of these moments of being reunited with the woman he loved…and how much longer he'd go on without one.

He tried to concentrate on the data, but soon became distracted again by the topic Pepper brought up, of the state of things with their new roommate.

Natasha had moved in almost two weeks ago, the day she'd asked him if he was okay with her staying in the Tower. Bruce had been surprised, first that she'd wanted to move in at all, after the awkwardness of their conversation, her discomfort with him evident, and then that she would do so immediately. Most of her stuff was in storage, she told him, and she'd send for it later if she needed it, but she'd brought a duffel bag of clothes and her laptop with her. She was one of those people, he supposed, who set her mind to something and then did it, without dithering. Come to think of it, probably a necessary quality for a spy.

Either that, or the collapse of SHIELD had left her truly desperate.

If there was anything Bruce understood, it was desperation. Hoping to put her at ease, he'd offered to give her a tour of the Tower, which Tony had renovated extensively following the Battle of New York to accommodate the Avengers as well as the divisions of Stark Industries based in the city. Natasha declined, not wanting to interrupt his work and saying JARVIS could show her where to stay. She wasn't rude, exactly, but she was distant. Which Bruce took as a hint that she preferred he keep out of her way.

Apparently he wasn't the only one preoccupied with Natasha.

"I know the Tower's big for three people," Pepper said, disengaging from Tony's embrace; Bruce thought he might have actually heard him whimper, "but what do you mean, you don't see much of Natasha?"

"She's invisible," replied Tony. He sauntered up to Bruce's desk and perched on the edge of it, a pile of notes crinkling as he sat on them. "That's what my fellow happy scientist and I have been up to. We invented an invisibility serum, so we literally don't see Natasha."

Again, Pepper looked to Bruce for a real answer.

"It's not that we don't ever see her," he said, taking off his glasses to wipe a smudge with the corner of his lab coat. "Usually I bump into her in the kitchen at breakfast."

"Really?" said Tony. "I never do."

"That's because breakfast is the meal before noon, Tony," Pepper said.

"I always thought that was brunch."

"Mostly she keeps to herself," Bruce went on. "She's on her computer a lot. Reading the news."

"That's what she wants you to think," said Tony. "Really she's on Tumblr, keeping tabs on the Hawkeye fanbase. Which reminds me, I'm weirdly unpopular on that site."

"Is it really weird, though, for a fifty year old arms dealer not to be popular with teenage social justice warriors?" Bruce mused as Tony leaned over him and commandeered the computer.

"Pushing fifty, and hell yeah, dealing arms-right into wormholes. How's that for social justice?"

"Really, Bruce," said Pepper, "the fact that you've lived with him for two years and haven't…you know…"

"I believe the term is hulked out," said Tony, ever helpful even while perusing social media.

Pepper's cheeks were tinged pink. "It's beyond impressive."

"Thanks," said Bruce, combing his fingers through his hair and tugging. Moving swiftly right along from the reference to the Other Guy, he said, "Natasha spends a lot of time in the gym, too."

"Maybe I'll ask if I can be her workout buddy while I'm in town. I could use some advice with my routine. I'm in a rut."

"Honey, I can totally advise you about your routine. Be my workout buddy."

"Aw, Tony, of course you can work out with me," said Pepper, heels clicking on the tile floor of the lab as she came to stand in front of him.

Bruce grabbed his keyboard back as Tony, still sitting on the edge of the desk, hooked her around the waist to draw her between his knees. Out the corner of his eye, Bruce saw Pepper trail her fingers down Tony's chest, then poke him in the stomach.

"He's been ordering from that shawarma place every day, hasn't he, Bruce?"

"I…" Bruce darted his eyes from Pepper, who stared at him from beneath an arched eyebrow, to Tony, who glared at him from beneath a furrowed one. He pushed his glasses up from where they'd slipped down the bridge of his nose, then placed them on the keyboard. "Sorry, but if I answer that question, I might hulk out."

For two weeks now, Natasha had been living in Avengers Tower with Tony and Bruce, and she could already distinguish between their knocks. Not that super spy skills were necessary for that. Tony preferred shave and a haircut-when he could be bothered to knock-and took it as a personal insult if she didn't answer with two bits, which of course she never did. Bruce's, on the other hand, was barely audible over the click of the laptop keys beneath her fingers, and usually followed by the sound of him clearing his throat, as though he were embarrassed to bother her.

This knock belonged to neither man: three sharp raps, confident and to-the-point. Maria Hill would've been a good guess, if she weren't in Washington for a public hearing which Natasha spent most of the day watching. A shame, because she'd found some potential HYDRA connections while studying the leaked files, and would love to float them by Hill. It would have to wait till she got back to New York.

Typing the sentence she was in the middle of to its conclusion, Natasha saved her work, minimized the window, and called out, "Door's open."

Swiveling in her desk chair, she contained her surprise to see the CEO of Stark Industries. No one told her Pepper was expected. Or maybe someone had-Bruce, at breakfast?-and she'd been too preoccupied to notice. An alarming prospect, confirming her fears that a sabbatical would make her rusty. To her relief, Pepper said it was a last-minute trip after she found herself unexpectedly free. She hadn't even told Tony till the plane landed.

"I thought he'd drive you and Bruce crazy if he knew I was coming in advance."

"As opposed to the rest of the time," Natasha deadpanned, getting up, the soles of her bare feet scuffing on the tile as she approached the other woman, "when he doesn't drive anyone at all crazy."

She arched an eyebrow, and Pepper's eyes glimmered conspiratorially from beneath her wispy bangs.

"I'm glad you're here now, so Bruce has someone to commiserate with. People who've worked closely with Tony Stark. It could be a support group."

"Or, he could just blame me for recruiting him to this circus in the first place."

Natasha's shoulders tensed at the reference to Bruce. Although his initial wariness of her was justifiable, given the revelations about her past, she'd hoped time would make him more comfortable with her, like Steve and Clint. She gave him time and space, but he continued to keep his distance, interacting with her only if they happened to be in the same place or the same time. You couldn't win 'em all, she guessed.

She rolled her shoulders to relieve the tension. Pepper watched; if she suspected there was a reason for it other than sitting too long hunched over a laptop at a small desk, there wasn't any indication of it as she came further into the room, circling it as if to inspect its contents.

"I think he's too much in scientist heaven to resent you for that. Even though I think Tony flirts with him even more than he did with you. Maybe you can give Bruce tips on how to shut that down."

"Or maybe he likes it. Jealous?"

Pepper gave the bland smile perfected by years of putting up with Tony, then leaned over the desk to get a closer look at the papers hanging on the magnetic bulletin board above it.

"Tony will be jealous of these, if he sees them. Are they from little Black Widow fans?"

She was referring to the drawings Cooper and Lila made for her during her brief stay at the Barton farm: stick children hugging or holding hands with stick Natasha…stick Black Widow and stick Hawkeye fighting stick Chitauri…pages ripped out of Avengers coloring books. Natasha was relieved Pepper apparently thought she had a valid reason to be in possession of children's artwork other than it having been made by her best friend's secret children.

"He's really bothered Iron Man doesn't do well with the teen girl demographic," said Pepper.

"I told him to stay off Tumblr," Natasha replied. "But come on, Cap and Thor? I know who I'd have been all over as a teenager."

Actually, as a teenager, she'd probably have used their faces for target practice in the Red Room.

"Don't sell yourself short." Pepper thankfully drew her back from that dark turn her thoughts had taken. "I bet more than a few teen girls are crushing on Black Widow. Or you're their first feminist role model."

She reached out to gently unroll the edge of one of the coloring book pages, where it had curled inward on itself. It was one of Cooper's, with no consideration for the lines or Black Widow's preferred color scheme, her suit suspiciously red, white, and blue. He'd presented it to her with mischief in his eyes-Clint's eyes-and she'd caught him in a headlock and given him a noogie. "Is this your way of telling me Cap's your favorite?"

Clint, watching the whole thing, said he was the one who should be most offended: "My own kid only ranks me third? Jesus, what do I have to do to get a little appreciation around here?"

Cooper replied that Hulk was actually first, then Cap, then Thor, then Iron Man. "You just have arrows, Dad. Arrows aren't very cool."

"You should have these framed, display them properly." Pepper straightened up, looked around the room again, eyes raking over the bare walls. "Just because this used to be Stark Tower doesn't mean that's a proscribed style of décor, you know. Feel free to do what you want with it."

"As you can see, my aesthetic is crayon on construction paper," Natasha replied. "I wasn't sure if this was like a dorm. Will I get fined at the end of the semester for putting holes in the walls?"

Although Pepper acknowledged the joke with a smile, she responded seriously. "That could be a long way off, couldn't it? The government hasn't exactly set a precedent for swift investigations."

Natasha couldn't argue with that point. And even when the hearings ended, HYDRA still posed a serious threat to anyone associated with SHIELD so long as the cells continued to operate and grow.

"That reminds me," Pepper said, "did you catch any of Maria's testimony today? I wanted to, but I had to be on the phone the whole time I was traveling."

Natasha ground her teeth. "It wasn't a testimony so much as an excuse for Colonel Talbot and General Ross to publicly chastise her."

"That's what I was afraid of, when I heard Ross was involved."

"He's a sick idiot," Natasha replied, thinking grimly that maybe sharing that opinion with Bruce would win him over a little. "Talbot's sincere, but also an idiot."

They grilled Maria for hours with questions that had no ready answers. Who was going to pay for the destruction in in DC, since SHIELD no longer existed, thus no longer carried an insurance policy? Was it fair to expect the citizens if the district to foot the bill for an organization that had been infiltrated by former Nazis? How, by the way, had the most elite special agents in the world allowed a breach of this magnitude? Then again, at least one of these agents was a former KGB spy, so should anyone be surprised to discover the whole place was infested with traitors and double agents?

"Do you anticipate being summoned again?" asked Pepper. "In any case, you should definitely consult with a lawyer, if only to put your mind at ease."

She pulled her phone from her pocket and began to text; the phone on Natasha's desk simultaneously buzzed as her computer chimed an email alert.

"That's his contact info," Pepper said. "He's gotten Tony out of…Well, I don't have to tell you what he's gotten Tony out of." She smirked. "Clearly, that makes him the best."

"And he's Maria's guy, right? I'll take that as a ringing endorsement."

On her way out, Pepper paused in the doorway. "I hope this is all settled quickly so you can get back out on your own and get back to work. But really, Natasha, however long you stay, make yourself at home. No offence, but with you six in this place, I don't think artwork's going to be responsible for the most holes in the walls."