A/N:

I seemed to be one of the minority that liked Natasha/Bruce in AoU. I really like Natasha as a character and I don't like it when people just use her as the cold-hearted, robotic assassin. This story is one of the ways you could get from the Natasha in Avengers to the Natasha in AoU.

Thank you to the incomparable Deejaymil for the beautiful cover. If you like words, you'll like her words so go check them out!

Chapter One:

She would care more about the knife to her neck if she hadn't just put her foot through a plate glass window. Without her tac suit on, she was pretty sure her ankle was going to be all kinds of shredded when she got a chance to check. Of course knife-to-the-neck guy was making that pretty difficult.

Natasha slammed her elbow up suddenly and with immense force, flinging the knife from the goon's hand. One flip later and he was gasping on the floor, the wind knocked out of his chest. Whipping a gun out from the waistband of her jeans she took out two more henchmen rounding the corner and flicked a shock disc behind her to take out the last one. A solid kick to knife guy's face knocked him out cold leaving her surrounded by broken glass, dead or unconscious bad guys, and the smashed remains of what had been a very pretty and extremely convincing Bernini sculpture forgery. Full of explosives.

Not bad for a Monday morning.

Suddenly the quiet was broken by the buzz of her SHIELD phone vibrating against her leg. She pulled it out and switched it to speaker phone, sitting down heavily, the phone on the floor next to her. Fury's voice echoed through the room while she rolled up the shredded leg of her jeans to start pulling the glass out of her ankle.

"We need you in New York, Agent Romanoff. I have a new assignment for you."

"Well I hope it's more relaxing than this one," she quipped, throwing a blood-covered glass shard to the floor.

"Just sent the briefing through." Fury hung up abruptly. He was never one for small talk.

Natasha stretched her ankle out, frowning when a few of the cuts beaded up with fresh blood. Picking up her phone again she opened the briefing and flipped through it. Her frown deepened.

"Bozhe moi."

XXX

It took Natasha longer than she'd care to admit to figure out the layout of Stark's new tower. Half the tower was still under construction and too many hallways were blocked off. After a little bit of wandering she found the elevators and asked JARVIS to take her to the level with Bruce Banner's lab. Before the door pinged open she took a deep breath and steeled herself for the awkward conversation to come.

Of course every conversation anyone had with Bruce Banner was awkward, but they hadn't really spoken much since the Helicarrier incident and she was pretty sure Fury hadn't warned him of what was about to happen. She fought side-by-side with the Hulk when the wormhole opened, but everything after that was a bit of a blur. Bruce had left as soon as Loki was gone, going back to the remains of Stark Tower with Tony to start work on the rebuild. He'd been ready to run again, Natasha had recognized panic in his eyes, but Tony, it seemed, had convinced him to stay.

It had been almost a year now since they'd all gone their separate ways and, besides Clint who she saw on a near daily basis, the only Avenger she had seen was Rogers. He was spending most of his time working for SHIELD and they'd done a few missions on the same team.

Thor was back in...space...or wherever he came from. Tony was in Germany "helping" Pepper with a new branch of Stark Industries and Bruce had stayed at the tower to oversee the last stages of construction and work on his research. Getting your own state-of-the-art lab in a billion dollar Superhero HQ/Playboy Mansion apparently had its perks.

And there was about to be one more perk, at least hopefully he saw it that way.

The elevator reached his floor and opened on a sea of glass and computer screens. Up a wide flight of stairs was a smaller room encased in glass. Bruce's private office. Bruce was decked out in a white lab coat, his back to her, papers in piles all around him, poking a screen and then writing things down. She managed to walk all the way up behind him without him noticing her presence.

"Hey, Doc."

"Gah-!" He jumped about six feet in the air, dislodging papers and nearly tipping his chair over backwards. He spun around, first looking startled at the appearance of anyone in his office, and then twice as stunned when he realized who it was. "N-Natasha. Um. Hi?" He took his glasses off and started resetting the paper avalanche. "What are you doing here? Not, not that you're not allowed here, I just thought that you were, you know, in DC, doing, ah, secret spy..stuff..." he trailed off lamely.

Nat couldn't help but smile, enjoying watching him babble himself into a verbal corner, as usual. "I was. I have a new assignment."

"Oh. I see. Good. Here? At the tower?"

"Yup."

"Why do they need...?"

Natasha sighed, this was going to be the tough sell. "It's you."

"What?"

"My assignment. It's you."

"Me?" Bruce's body language started to tense up and close off.

"Yup. I'm your new bodyguard," she stated, deciding bluntness was the best policy.

"Bodyguard..." Bruce stared at her for a moment before breaking out in cold laughter. "Don't you think I'm the last person in the world who needs a bodyguard? I have a built in bodyguard, what on earth could happen to me that I'd need protecting."

"Well it's not really you I'll be protecting, Doc. My assignment is to keep you from, uh," she searched for the right word, "changing. It's to protect everyone else. It seems like you have it almost entirely under control, but getting hurt or scared can be the tipping point. My job is to stop that from happening in advance. If I keep you safe, you stay you."

"Well you could start by not creeping up on me and giving me a heart attack," he pulled off his glasses and looked at her. The corner of her mouth twitched up slightly, but she remained silent. "I'm not a SHIELD agent."

"No one said you were."

"But Fury sent you here?"

"Yes."

"And if I say no?"

Natasha smiled, her mind rocketing back to their first meeting. "I'll persuade you."

Bruce couldn't help but smile at that too. "Seriously though, they're throwing you between me and the bullet to stop the Other Guy from making a mess of Manhattan?"

"Basically, yes."

"Why now? It's been a year since the Chitauri with no, um, problems."

"That I'm not entirely sure about. It seems SHIELD has been keeping an eye on you. Perhaps there has been some chatter that got their backs up. That or Stark has been gone too long and they don't like the idea of you here alone." She shrugged. "I just go where they tell me to."

"Why you?"

Nat hesitated. Her stony exterior failed her briefly and she looked down at the ground. "They wanted someone with experience. Someone who would take it seriously, understand the transformation. Someone who wouldn't be so terrified they'd bail when things got stressful."

"So they sent you."

"Yes."

"Geez, Natasha, I tried to kill you, why would you want to work with me?"

"Actually you never tried to kill me. The Big Guy tried to kill me once, yes, but he also fought beside me and saved my life more than once. I'd say we're even. And like I said, I go where they send me." She dropped her bag on the floor and sunk into a nearby chair, arching a brow. "Besides, if anyone should be motivated to keep the green guy under control it should be the gal he wanted to kill."

"That's not funny."

"Kinda is." But Bruce wouldn't shake the grim expression he'd adopted. "Look, Doc. It's my job and I'm damn good at it. Fury chose me to go, he's usually pretty good at that kind of thing. If you want me gone, you can take it up with him, but I am done fighting that guy on stuff like this. It's like trying to eat soup with a fork. A really angry, one-eyed, fork."

Bruce deflated into the chair opposite her, letting concern crease his brow. He spoke quietly. "I don't want to hurt you."

"I know." She spoke matter-of-factly.

"You really think I'm in danger here at the Tower?"

"After New York we've been plastered all over the media. There have been pictures of you and the Big Guy all over every news outlet from here to Sydney. People see power and they're going to want to take it. Yes, I think you're in danger and so does Fury. It also wouldn't hurt to have a SHIELD agent here to liaise with the rest of the Avengers Initiative. SHIELD wants to keep Stark as an asset and if Thor finds his way back and needs help, this is where he'll come. With Rogers and Barton in DC, it's a good idea for me to be here."

"Good idea...yeah.." Bruce stared at the floor, tapping his fingertips together and pondering. Natasha stayed quiet, letting him think it over. "You're being awfully open about all this. I'm surprised you didn't just come to stay, with some kind of cover story. Tony wouldn't have minded you moving in."

"It's a lot easier to protect someone if they know that's what you're doing. Besides, I was under the impression you didn't like being lied to." Her face was carefully blank, as usual, but she let her eyes warm a little, show him she wasn't angry or bitter.

He flinched at the memory, but ultimately sighed and leaned back in his chair, pinching the bridge of his nose between two fingers. "Okay. Fine. So what does this entail? You wearing black sunglasses and an earpiece and standing behind me while I work? It's pretty boring most of the time."

She let a smile twitch at the corner of her mouth and reached into her bag. "Not exactly."She handed him a small black fob, with a large, stiff button in the middle. "This is your panic button. If you push it, I will come. No matter what, no ifs, ands or buts. You need help, you feel green around the gills, a guy looks at you funny? You push it, I'll come." She held up her wrist showing him the watch that would alert her to any button pushes. "Okay?"

"Okay." Bruce took the fob and looked it over. "What if it's a false alarm?"

"I don't care. You push it, I'll come."

"So if I think the Other Guy is going to make an appearance?"

"You push. I come." She pointed first at him, then at herself, over-enunciating the words as if to a child.

"That's not the direction you should be heading in." He looked pained at the thought.

"Well my hope is that you'll push it well before that and I can stop it from happening at all, but if it comes down to it I need to know so I can call in the team and try to get you contained. Deal?" She waited until he nodded and clipped the button to his belt loop. "Good. Other than that it's just a matter of me keeping an eye out, knowing your schedule. I'd appreciate it if you could give me a heads up when you're going out so I can scout the area ahead of time."

"I don't really, uh, do that," he said, blinking around at his lab like he was seeing it for the first time.

"Do what?"

"Leave."

She actually did laugh at that, rising gracefully out of her chair. "Well, it should make my job easy then, Doc." She lay a hand on his shoulder as she walked past and she felt him flinch.

At first she tried to give Bruce his privacy, only checking in on him once every other day or so. The truth was, Bruce did make her a little nervous. Their incident in the Helicarrier had been one of the most terrifying events in her very interesting life and she had no desire to repeat it. She came here because it was her job and she wasn't about to start turning down jobs because she was scared. She crossed her fingers and hoped Bruce wouldn't be showing off his "party trick" anytime soon.

She mostly stayed in her room and read or worked on some of her research-based projects for SHIELD. She texted back and forth a lot with Clint and, after a week of boredom, ultimately gave in and watched Stark's enormous TV. Finally she took to just wandering the halls, trying to memorize the layout of each new floor as it was completed.

The bottom half was now Stark Industries, all specialty R&D. After that you needed special Avengers clearance. Stark shared the lab with Bruce, but he also had a private workshop which was the first of the Avengers floors, with a large glass window overlooking the two floors below. He said it kept him connected to the business, but Natasha was pretty sure he just liked to watch the engineers playing around. It inspired him.

Above that was a massive three-story space that included a large gathering area (which Tony insisted on calling the "party room" and a quieter balcony above it with comfy chairs and couches. The highest of the three levels was a large lab that Bruce used for his research or shared with Tony when they were both there. Bruce had his private office off the main lab.

The Quinjet bay was only a few floors from the top and was still partially under construction. Nat wasn't really sure what was going in on the top few floors, perhaps Tony didn't even know yet, but there were always a number of workmen up there pointing at blueprints and frowning.

In her explorations she found a small theater, three kitchens that always seemed to be stocked, two gyms, a pool, a library and an enormous closet full of a variety of cleaning robots that JARVIS could summon to anywhere in the building.

Tony had hinted that there were better living quarters to come, but for now two of the floors had a bunch of simple suites in each one. Bedroom, bathroom, living space - plain and straightforward. Each floor had a big kitchen and rec room. The kitchens were stocked by JARVIS-ordered deliveries that she never seemed to see or hear. She chose a room on the same floor as Bruce's, but down the hall a ways, wanting to be nearby just in case, but not wanted to crowd his privacy too much.

She didn't go into Tony's private workshop and to be honest she wasn't sure what would happen if she tried. Stark was the kind of guy where it seemed equally likely that he would leave the workshop totally open, lock it completely, or leave it open but fill it with booby traps. She didn't really want to find out which.

One evening, about a week after arriving she wandered down to the kitchen for some dinner and ran into Bruce. He had his sleeves rolled up and was standing, back to her, chopping something on the counter. He hummed softly to himself while he worked.

"Hey, Doc," she said softly, not wanting to surprise him. He stopped chopping and turned to look at her.

"Hi, Natasha. What are you up to?"

"Oh, I was just looking for something to eat. I'll just grab some toast or something." She pulled open the fridge and started rummaging.

"If you don't mind waiting you're welcome to share this." He gestured at his chopping.

"You cook?" Natasha asked, pulling a juice box out of the fridge and sticking a straw in it.

"Yeah...I mean, I'm not, like, good or anything...I just. Make food." He shrugged.

"Sure," Natasha said, sitting down at the kitchen table.

"What?" Bruce looked kinda lost standing there with a knife, dripping tomato on the floor.

"Yes, please." Natasha's lip quirked up into a smile around her straw. "I'd love some."

"Oh. Well good. It'll just be a little longer."

"No rush. Do you mind if I hang out?"

"Not at all." He turned back to his tomatoes. They stayed in silence for a while, Bruce bustling about the kitchen, turning on the burner and adding things to a pan until the lovely smell of cooking tomatoes and spices filled the air. With the food to focus on, Bruce relaxed more than usual and Natasha was able to get a look at the real him. He carried the Hulk around with him like a weight on his shoulders, it was interesting to see how tall he could stand when he set it down for a moment.

After the last few weeks her fear of him had abated somewhat – it was so hard to remember to be afraid when faced with this mumbling, shy, goofy, nerd.

About twenty minutes later Bruce pushed a plate across the table to her. It had rice and a strong – but delicious – smelling spinach and tomato curry.

"I hope you don't mind curry," he said. "I pretty much did all my learning how to cook in India."

"It looks great, thanks." She accepted a glass of wine from him as well and they sat down together. Without the cooking to focus on he shifted back into awkwardness and fiddled with his fork "So why India, anyway?" She asked, trying to break the unpleasant silence.

"I don't really know. I guess I thought I could be helpful. It's also easy to stay out of big cities if you want to. I just wanted to focus on something...new."

"You know I never thanked you," Natasha said.

"For what?"

"For coming back. Last year. For fighting with us. I know it wasn't easy for you."

"I wish it had been, but you're right, it wasn't. I almost didn't...I'm glad I did, though."

"I'm pretty sure Stark is too." That got a quiet chuckle out of him.

Two glasses of wine and a second plate of curry in each of them and they both relaxed a little more. Natasha told him a few of her tamer stories of life in the field, and he tried to explain what he was working on to her. Nat considered herself pretty damn smart, but she wasn't even sure half of what he said was real words.

At a break in the conversation Bruce leaned back and looked at her thoughtfully. Finally, he pulled his panic button off his belt and put it on the table. She was relieved to see he was carrying it around with him all the time.

"So what happens if I push it?"

"I'll come," she said automatically.

"No, I mean how do you know where I am?"

"Push it," she said nodding to the little button. He raised an eyebrow at her and she nodded again. He picked it up again and pushed the button. Immediately the watch around her wrist started buzzing against her wrist. She reached out and pressed it against his arm for a moment so he could feel it. With the touch of a button a map appeared on the screen and she was able to zoom in and out, two tiny dots overlaid on top of each other – green for Bruce, red for her.

"Why doesn't it make a noise or something?" he asked, holding her wrist and poking at the watch, playing with the screen like a kid with a new game system.

"In case I'm in a stealth situation," she answered frankly. "This way only I know it's going off. Don't worry I won't miss it, it's pretty hard to ignore."

"I'm not. Worried, I mean."

"Good."

"I was just curious. What it was like at your end."

"Yeah, well next time you can be the spy and I'll be the scientist," she joked. "Of course I'll probably end up blowing something up."

"That's okay, it'll be just like having Stark home." They both laughed. She felt warm and more relaxed than she should have while on a mission. She stood up and cleared both plates into the dishwasher, following up with the cutting boards and knives Bruce had used. He put the leftovers in a container and tucked them in the fridge. For a moment they both just stood awkwardly in the kitchen, not sure what to do next.

"Well, I should probably..." Banner gestured vaguely towards his lab.

"Of course. I have to call in a report anyway. They'll know the button was pushed and if I don't report in within a few hours this place will be swarmed with helicopters."

"Oh. Yes. Well, you'd better do that then."

"Night, Doc."

"Goodnight Natasha."

She slid out of the kitchen feeling his eyes on the back of her neck as she walked down the hall back to her room. She sent in a quick report and then lay back on her bed. She felt the heat of the wine flush her cheeks. She had a very high tolerance for alcohol – she was Russian after all – but the spices in the curry and the relaxed chatter had exaggerated its effect and she was feeling ready to drift off to sleep.

Forcing herself to get up and change into her pyjamas she curled back under the blankets wondering if being stuck at the Tower was going to be that bad after all.

XXX

The next night around 6 o'clock her phone binged with a text and she pulled it out. It was from Bruce.

Hungry?

She put down her book and smiled. She made her way back down to the nearest kitchen and found Bruce up to his elbows in cooking again. Pasta this time.

The conversation came more easily this time and before long they were laughing and joking. Natasha found herself getting a little flirty, as she often did, and she enjoyed the stammer she could get out of Bruce when she did.

The threat of the Other Guy drifted away for her and she started to forget sometimes that this was an assignment. She'd gone this long, and longer, without excitement before, but she'd been constantly deep in the action for a while and despite a natural propensity for danger, it felt kinda nice to relax.

After that night, dinner became a regular thing. Nat started bringing her book to Bruce's lab in the afternoon so she could follow him down to the kitchen when they got hungry. She'd show up earlier and earlier and he always seemed happy to see her. She found him nice to be around, he was quiet and surprisingly funny.

She even found herself hoping she'd be able to earn his trust eventually. He still had this way of flinching away from her when she walked by too close or leaned over him to grab something.

Sometimes he would bounce ideas off her, talking out problems in his research often with a lot of arm waving and creased eyebrows. She would half-listen commenting with a Steve-esque, "I understood that reference," the rare time she heard a technical term she understood to remind him not to expect much help from her.

Life in the tower became comfortable and quiet, shrunk down to just the two of them, on the one floor of their giant tower in a giant city.

They continued to eat dinner together every night and Natasha started spending most of every day sitting in the corner of Bruce's lab, reading or typing on her laptop. The corner slowly shifted more and more into her space until she'd built a mini-zone just for her. Bruce didn't seem to mind at all, in fact he seemed to be shifting things around to make more room for her things.

One day she was curled up in her chair, shoes off and feet tucked under her when a series of impressive expletives came from under the fume hood.

"Are you okay?" she asked, raising her eyebrows. "I didn't even know you knew some of those words."

"I'm fine, it's just this fucking- damnit..I- DAMNIT." There was a slight foof from between Bruce's hands and he pushed his chair back, clenching his fists.

"Bruce?" she was more serious now. "Are you okay?" He looked up and his eyes widened when he saw she was standing poised to move, book discarded on the floor.

"Sorry, I'm sorry. I'm fine. It's not..it's not real, I'm just...frustrated." He took his arm and swept it across the table, pushing everything into the bin with a "Hazardous Waste" warning on the side. A cleaning robot zipped out of a cupboard, picked up the bin and zoomed off. "Overzealous little bastard." He pouted, tapping his foot against the edge of the table. "Sometimes it feels like working at the Sirius Cybernetics Corporation. We'll be the first against the wall when the revolution comes."

"I have no idea what you're talking about."

"It's nothing, it's stupid. I've just been working on this for a while and it turns out it's not going to work." He ran a hand tensely along his neck and up through his hair.

"Oh, sorry." She wracked her brain, trying to remember what he'd been telling her about. "The thing with the..uhh..." she moved her hand in the shape she was trying to recreate – he'd shown her pictures. "The little honeycomb particles?"

He laughed at her description. "Yeah, that's the one."

"Sorry," she repeated.

"Oh, well. I'll find another way."

"Wanna go kick the crap out of something?"

"What?"

"You know, go workout, vent the frustrations, hit something. It always works for me."

"Oh. I don't really do that. I was never taught...I mean I run, it's good for my heart rate control, but I don't really, uh, hit things."

"Wanna learn?"

He blanched. "Is that really such a good idea?" he asked quietly.

"Of course it is. Trust me, you'll feel better. It'll make you less angry, not more. Plus, if you're good, I'll teach you some more swear words." She couldn't help but slip a little innuendo into her voice, enjoying the red flush that worked its way up the back of his neck.

"If you think it's okay..."

"C'mon." She left her shoes by the chair and grabbed Bruce's sleeve, pulling him down the hall after her. At the door to his room she let go. "Put on some sweats and meet me in the gym in five minutes."

She was already in stretchy clothes so she went straight to the gym to warm up. Tony's gym was amazing and had everything – she wasn't even sure what some of the stuff did. One whole wall was entirely mirrors and there was even a barre. She ran her hand along the barre, a thousand memories bombarding her. She hadn't danced in years, but muscle memory took over and she found herself rising up on her toes and lifting her hand up.

She ran quickly through a handful of warmups and stretches and then, since Bruce still hadn't arrived, she asked JARVIS to put on the music to an old favourite solo of hers. It was light, dreamy and slow. She couldn't remember the whole thing but she slid in and out of the parts she did know, improvising when her memory failed her. She enjoyed the light pain in the joints and muscles she didn't use for her normal workouts, pressing into the stretches and pointing her bare toes. She heard Bruce slip in, but she didn't stop and he waited quietly, watching.

She floated through the rest of the routine and finished with her nose pressed to her calf, one leg pointed high in the air and one flat on the floor as the music drifted to a close. Reaching out she put her hands flat in front of her and rolled into an easy handstand, chuckling. Not exactly a "classical" finish.

"Wow, that was amazing," Bruce said from his spot near the door. "I hope that's not what you're planning to teach me cause I'm pretty sure my body won't do any of that."

Natasha laughed and bounced over to him. She was feeling good and the unusual exercise had given her a slight rush that she usually had to work out for hours to get. "Don't worry, you get to do something a lot more fun!"

She started out showing him how to stand, how to find his balance and how to brace himself. When he was ready she grabbed the pads and stood in front of him, padded hand held out. "Okay hit me."

"What?"

"I wanna see what we're working with. Hit me."

"Uhhh..."

"Really? Please don't tell me you're uncomfortable hitting a girl."

"It's more that I'm uncomfortable hitting anyone, actually." He shuffled from foot to foot.

"Come on, Doc. Don't you want to feel more in control? Right now, if you get threatened in the slightest, the Big Guy shows up. Maybe, if you could fight back a bit, protect yourself, he wouldn't feel the need to protect you." He looked a little softened, but his eyebrows were still pinched together."I'm not trying to turn you into a soldier," she added quietly. His eyebrows moved from pinched to surprised and she saw she'd touched a nerve.

Seeing the determination in her eyes he nodded and braced himself. "Okay, fine."

It turned out that he wasn't that bad really. They spent the next hour working on his form and by the end he had a pretty formidable right hook. She'd still be able to drop him in a second – a fact she reminded him of regularly – but his confidence had grown even in just the one session.

They kept it up and one surprising result of their sparring sessions was that Bruce instantly seemed more comfortable around her. He no longer flinched away constantly, though he still had a personal bubble the size of Texas.

A few weeks later Natasha expressed an interest in helping in the kitchen and Bruce set to work teaching her how to cook.

Nat was a very fast learner, but she struggled with the freedom and fluidity of cooking. Sometimes Bruce would change his mind halfway through something and go in another direction and she found it frustrating. Soon though she began to see the fun in experimenting and she starting mixing up herbs and spices in new and exciting ways and making him try them.

"It's kinda like mixing explosives," she said, coming into his office one day and holding out a bowl with a new spice mix in it. "You kinda know what you're going for, but the result can still really surprise you."

"Hmm, that's encouraging." He raised an eyebrow at her doubtfully, but dipped a finger in and tasted it. "Wow, that's really hot-" he coughed a little, "-...but nice."

"Have you ever eaten something so spicy you turned green?" Natasha asked cheekily, sliding into his comfort zone. He gave the redhead an exasperated look he saved for when she wasn't taking his 'condition' seriously enough. By now she'd learned just to ignore it.

"Umm, hi?" said a small voice from the doorway and they both turned to look. A tall girl with purple hair and a lip ring, holding a stack of folders was standing nervously by the door, looking pointedly at the floor.

Bruce suddenly realized how close they had been standing, leaning towards each other over the spice bowl and he stumbled backwards, bumping into his desk. Nat couldn't help but smile, he was such a dork sometimes. She set the bowl down and walked over to the newcomer. She was wearing a SHIELD badge and a terrified look.

"Who are you?"

"I'm Lillian Banks? From accounting at SHIELD? I'm new?" she added, as if that wasn't obvious. "I'm supposed to, uh, do some expense reports, surveys of the new building?"

"Oh." Nat must have dozed off during that briefing. "I thought Stark was paying for all this."

"Oh, yes, well he is? But as a donation to SHIELD in some parts...sooo...I have to..uhh. Do this." She indicated the folders. "I didn't mean to interrupt...anything." Natasha wasn't sure who was blushing more, the girl, or Bruce. She decided to put them both out of their misery.

"Not a problem. I was absolutely expecting you. Just let me know what you need to see." She gestured for the girl to lead the way out of the lab and towards the elevator. She fumbled with her folders, pulling out a list of numbers to acquire and starting rattling things off to Natasha. As the elevator doors closed Nat looked up and saw Bruce turn back to what she thought of as his "chemistry set". She was pretty sure it had a more technical name, but he was always doing things that looked like a scene from Great Mouse Detective with beakers and strange chemicals and Bunsen burners. She liked the idea of him as a kid doing the same with a set bought out of the back of a comic book.

What Agent Banks needed to see was fairly straight-forward but it did take some time and some of the info was hard to find. They hit the upper floors that weren't done yet and she chatted with the workmen about some of the future plans.

Natasha found herself mostly useless except as a table when the girl started handing her files, looking for a particular one buried deep in the stack. Arms full of papers, Natasha let the chatter turn to noise as her mind wandered off into space.

And that's when her watch went off.

The second the buzzing started Natasha dropped the folders on the floor and started racing down the hall. She heard the accountant calling after her, but she slid into the elevator JARVIS had called without pausing. Rocketing down 17 floors she pulled her guns and checked the ammo.

The lab was quiet and empty but a groan from up the stairs drew her swiftly into Bruce's office. The second her feet crossed the threshold she hit the brakes.

"B-Bruce?" She tried and failed to keep the stammer out of her voice. He was leaning forward over the table, gripping the metal so hard it had bent. There was a slight green tinge to his skin and a terrifying depth to the grunts that came with every breath. He didn't speak but a slight incline of his head acknowledged her presence.

Skirting along the wall to his right slowly and cautiously, Natasha noticed a pile of broken glass under the table and a slow drip, drip of blood coming from Bruce's right hand. Willing her legs to stay upright and her breathing quiet she inched her way across the room towards the table. "Bruce?" she asked again, quieter but more stable.

He looked up at her and she saw the pain and fear in his shifting green eyes. "It's okay, Bruce, you're hurt, but you're okay. You're going to be fine. Just breathe. Just breathe." Natasha repeated those words like a mantra, each tiny step bringing her closer to him.

Turning away from her, a low growl tore out of his throat and he gripped the table harder, mangling the metal edge. Her hand shaking Natasha shifted closer, desperate to get him to release his right hand and stop the metal from digging in and making the wound worse, adding more pain to fuel his transformation. "Bruce," her voice was pleading and needy, as she struggled to keep herself in the present, memories of watching him shift on the Helicarrier floor threatening to surface.

She desperately wanted to remove his hurt hand from the table. Not knowing what else to do, she reached out and placed two of her fingers shakily on his arm, her thumb tucked under, trying to make it look as least like a fist as possible. The second her skin touched his he let out a long shuddering breath and ducked his head lower.

His breathing sounded a little quieter, his grip a little softer so she kept going, sliding her fingers slowly up his forearm and back down. They seemed hung in the moment, Bruce on the edge of the Hulk and Natasha, one hand braced against the wall, her back to the table, arm stretched long to reach his, tracing his pulse with her hand, willing it to slow.

Finally, it seemed he was coming down, breathing slowing, a normal hue returning to his skin. Finishing a line down his arm, Natasha kept going, sliding her fingers right across the top of his hand until her hand was resting on his. His grip finally released and he staggered backwards, sinking into a chair, his good hand coming up to cover his face.

Natasha let out a long, shaky breath, finally letting herself sink down onto her knees, taking a moment to calm her racing heart and gain control again. She kept his hand clutched in hers almost as a reflex and when she looked up she realized he was bleeding still.

She grabbed a clean towel from a bin by the desk and was about to press it against the wound but stopped, hesitating.

"It's okay," he whispered, his voice hoarse, and she met his now brown gaze. "I'm okay now."

When she didn't move he brought his other hand over to press the towel against the gash. Snapped back to herself she started moving again, gently pushing his good hand away and wrapping the towel tight beneath his fingers. "Sorry. I didn't want to hurt you."

"I'm okay," he repeated.

"What happened?"

"I was trying to test the validity- I just, um, I was measuring." He gave up on the lengthy explanation. Two dark circles had appeared under his eyes. "The beaker broke, cut me up pretty bad."

"I can see that." She grabbed a first aid kit from the corner and set back to work patching him up.

"I couldn't..." He trailed off.

"You pushed your button." She stopped her movements and looked up at him.

"Yeah..."

"Thanks."

"You're thanking me?" He chuckled. "You always get things so backwards Natasha. I don't think I'll ever understand you."

She smiled too. "Yeah, I get that a lot." She went back to bandaging his hand. The cut was pretty deep and she thought he probably should have stitches, but she was pretty sure her hands were too shaky for that. "Soo, I thought you said you had pointy things under control."

"Pointy, yes. Gushing blood, not so much."

"I see. So it wasn't the spices then?" That finally got her a cautious chuckle. All was quiet for a moment.

"How- how did you do that?" he finally asked. She just stared at his arm and shrugged. "Nothing has ever brought me back when I was that close." He met her eyes and they just looked at each other for a moment. Pulling her eyes away from his she brought them back to his arm.

"I just..." She reached out and gently touched him with her fingertips, right at the pulse point on his wrist. He didn't flinch away, but he froze, as still as stone. They hung there for a moment in silence.

Breaking the spell, Natasha leaned back and starting cleaning up the first aid kit, tucking everything back in its spot. Bruce reached out and grabbed her upper arm, waiting until she looked him in the eyes. "Natasha...thank you."

"Always," she replied. "You push it, I'll come."

He just nodded, giving her arm another gentle squeeze before sliding back into his chair and closing his eyes with a sigh. "I'm exhausted. I'm going to go lie down for a bit. You okay?"

"I'm fine. You go." She helped him up out of his chair. "I'll clean up and put in a report."

JARVIS sent one of Tony's cleaning robots to clean up the glass and blood while Natasha put away the rest of the supplies. She hit the lights as she walked out and headed straight for her room. She asked JARVIS to let the SHIELD agent know what had happened. A few moments later the AI let her know that Agent Banks had everything she needed and had left.

She pulled out her tablet ready to call in and make a report, but as the adrenaline had finally worn off and she just found herself utterly exhausted. Stripping off her blood and sweat stained clothes she climbed into a hot shower and let the steam wash the past hour away. Her mind wandered back to his strangled groan, his tense shoulders rippling as they threatened to turn green and she couldn't help but imagine what could have happened if she hadn't stopped him. With no Thor there to distract him, he would have ripped her apart, ripped the tower apart. For the second time in as many years she had been sure she was going to die at the hands of an ally and all because of a bit of broken glass... A tiny, strangled sob wiggled it's way out of her chest but she shoved it back in, gritting her teeth and turning the water to cold.

A few minutes later, clean and dressed in fresh clothes, she sent in her report to Fury:

Banner button push at 15:00.
Accidental wound triggering Hulk response.
Code Green Averted.

XXX

The next morning Natasha found Bruce in the kitchen, wrestling with a jug of milk. His bandaged hand was making it hard to get a good grip and he finally sighed and gave up, setting it back on the counter. She came over and took it from him, popping the top off and pouring it on his cereal. He sighed again and grabbed a spoon. She popped some toast in the toaster.

After eating in silence for a while Bruce waved his spoon in her direction. "Helen is coming by later. She said she'd patch me up."

"Oh. Good." Nat tried to summon some enthusiasm, but there was something about Helen Cho that rubbed her the wrong way. Cho was one of those people who acted like she'd known someone for years only moments after she'd met them and irritated Natasha to no end. Not to mention Bruce seemed to have a wild crush on the woman and the stammering and awkwardness always reached unbearable levels in mere moments. As soon as she showed up the two of them would start with the science talk and Nat would go back to being the outsider she usually was. She'd kinda of gotten used to being on the inside here.

She made an excuse to slip out and decided to go for a run instead of hanging around the tower. When she got back, Dr. Cho was in Banner's lab. She had his hand out and un-bandaged and was repairing it with some kind of laser suture.

Nat stuck her head in to see how it was going. "Hi Doctor Cho," she said, giving her a stiff wave. "Bruce back in one piece?"

"Oh hello. Not just yet but he will be." She smiled at Bruce and he smiled back. Nat felt an unfamiliar twinge in her stomach.

"Hey, Natasha." Bruce turned to her. "We're going to go out to dinner later. Is there anything you have to do? Clear the area or something?"

The twinge turned into a lump of rock and settled in her stomach to stay. "No, that's fine," she said shortly. "Just text me the name of the place and bring your button."

"You know you're welcome to come," Helen said politely.

"Thanks, but I have a lot to do," she said, more curtly than she intended. Bruce looked a little surprised, but she turned and walked out before she could say anything else mean. Helen was always perfectly nice, but Nat just couldn't hide her irritation. For someone who prided herself on revealing no emotion, it was beyond frustrating when she struggled with it.

She killed the next few hours watching TV and doing nothing and when her phone finally buzzed with Bruce's restaurant text she sighed and dialed Clint.

"Hey Babe, what's up?" he answered. She could hear the tell-tale twing of his bow in the background and distant sounds of gunfire.

"You busy?" she asked.

"Nah. Just doing some recon with the Cap. I only need one ear, go ahead."

"I wasn't calling for anything specific. Just bored."

"What're you and Banner making for dinner this time? Did you learn to make beer yet?"

"We're not making beer, you ass. Besides I'm alone tonight." She paused. "He went out with Dr. Cho."

"Oooh." Clint laughed. "Who's the green monster now?"

"I'm not jealous."

"Sure you are. Your boyfriend's got a date with the doctor lady. Of course you're jealous." His tone was teasing but it pissed her off anyway.

"He's my assignment, Clint. I just don't like her. I always feel left out with those two – they only speak scientist."

"Hate to break it to you, Babe, but that's jealousy."

"Banner is my assignment," she repeated.

"You don't have to be all mushy about someone to get jealous, Nat. You've been a terrible twosome for months now. You're keeping him safe – you've already proved you can – and now he ditched you for another. Revel in your jealousy. Own it. Give him some Black Widow sass-" There was a grunt and she heard the phone hit the ground. She heard some thumps and some distant swear words from Clint. She idly poked at her toenails while she waited for Clint to come back, wondering if she was bored enough to paint them.

A final thump, followed by footsteps and then Clint's voice came back on the line. "-It'll make you feel better.."

"Nah. I think I'll just leave them alone until she goes. Maybe I'll go out in New York more. I'm probably getting cabin fever in here. I've forgotten what the real world is like."

"From where I'm standing the real world kinda sucks. Plus it's really cold."

"Maybe you should get some sleeves then, Hero. Where are you, anyway?"

She could feel him shrug over the phone. "Somewhere cold?"

"I should go, let you get back to shooting things. Say hi to the Cap for me."

"Okay, talk to you later, Babe."

"Night." She hung up and tossed the phone away. Maybe, just maybe, Clint was a tiny bit on to something. They finally had this whole stuck-at-the-tower-together thing sorted out. Yesterday seemed...important...somehow, but he'd pointedly ignored talking about it in the morning and now he was waltzing off with his scientist girlfriend and leaving her here. She had read his files and for someone who had spent as long as he had trying to find a cure or control for his transformation, he was awfully uninterested in the fact that she'd brought him back from the edge so easily. What if there was something there? Something they could use?

Well, at least she hadn't said yes to dinner with them. As a spy Natasha had to deal with a lot of uncomfortable situations, but third wheeling it with Cho and Banner was painfully awkward. She was a little jealous and a little pissed at Bruce. Those feelings were so odd and domestic for her, it just made her feel even more uncomfortable.

She spent the rest of the night eating junk food and making a mess of her room. JARVIS had located some nail polish jars that Stark had been using for a bizarre experiment and she spent an embarrassingly long time painting a different pattern on each toenail. She knew her hair was sticking up from her run and her clothes were sweaty, but she didn't bother changing.

Bruce arrived back at the tower earlier than she expected and she was more than a little startled when he stuck his head in her room. He took in the mess and her crumpled appearance. "You okay?" he asked.

"Huh? Yeah, I'm fine." He looked so concerned she couldn't help but give him a reassuring smile and his whole body relaxed.

He fidgeted for a bit, not looking at her. "I was worried you might be freaked out from yesterday. I honestly thought you'd ask to leave."

"What? Why?"

"I almost killed you. Again." His voice was flat, but she could feel the strain in it.

"But you didn't. That's why I'm here. To prevent the Big Guy from making a guest appearance."

He gave her an exasperated look. "I thought it was more to stop people from shooting at me, or trying to blow up the tower, not to grab me while I'm halfway to green!"

"It worked, didn't it?"

"That's not the point." He ran a tired hand across his face.

"You pushed your button," she reminded him.

He sighed, finally looking her in the eye, then shrugged. "I said I would."

"Then it seems like Fury was right. It works. You push it, I come, Code Green Averted, everyone keeps their arms firmly attached to their bodies." She gave him a stern look and repeated, "That's why I'm here."

His body deflated as he gave up the fight. "Okay, fine." His grimace morphed into a tentative smile. "Thank you?"

"Anytime. But I'd prefer not anytime soon." Her voice was gently mocking and he rolled his eyes. Suddenly she wanted to change the subject. "Where's Doctor Cho?"

"Oh, her plane just left."

"Really, I thought she was going to stay."

"Nah." He shook his head and twizzled his hands together. "I mean, she offered, but I knew she was busy so I said... you could take care of me." He paused. "...right?"

He looked truly nervous that she might say no and Nat couldn't help but smile again, her frustration from earlier vanishing. "Of course."

"I got the impression you two don't, uh, really get along that well," he stuttered out.

Natasha opened her mouth to correct him, but realized it was silly to protest. She hadn't exactly been subtle. "It's nothing. It's my fault. She's smarter than me, you know how it is. Well, I guess you don't actually." She smiled to herself. "I'm sorry. I was rude."

"No, no. It's okay. This is your home too. If you don't like her..."

"Don't be silly, Doc. I'm just having a bad day. She can come anytime. I'll be nicer next time. I promise."

"Are you sure?"

"100 percent."

"Okay." He leaned against the door frame. "I mean she probably won't come back until one of us needs medical care again, which will hopefully not be for a while. She helped me with the project I got stuck on though." He remembered her earlier description and added with a small smile, "The one with the honeycomb particles."

"That's good." Natasha was pleased to hear a genuine inflection in her voice.

"I'll show you tomorrow. It's really cool."

"That'd be great." She smiled at him warmly and he looked around at the odd collection of chip packets and nail polish colours.

"Sooo, dessert?" he asked, "JARVIS says we have Oreos and ice cream." He paused, looking pointedly at the mess. "I didn't know you'd already eaten most of the junk cupboard."

"Like I said, bad day. Lead the way to the dessert, or risk life and limb."

"Yes, Ma'am."

Natasha pushed the polish bottles aside and leaped up, following Bruce down the hall as he described the latest idea he had had in great detail, drawing incomprehensible chemical diagrams in the air with his fingers.

It's your home too. She couldn't shake those words. The tower wasn't really her home, it was just home base for this assignment. But it was nice that Bruce thought that. That he was willing to share his home with her.

It's your home too. It would actually be kinda nice if that were true.

XXX

The next few months kind of drifted by. Bruce had no more beaker accidents and Natasha started to relax again. Every few days she would drag Bruce to the gym and make him practice basic self-defense. He progressed pretty quickly and soon they were working on gentle sparring. They didn't talk about that day in the lab, but his personal bubble seemed to get a little smaller. She found him occasionally leaning over her to see what book she was reading, or poke her in the shoulder when she sassed him too much.

His work seemed to be moving along nicely too, until, suddenly, it wasn't. She heard some grumbling from the other side of a large, complicated hologram and finally, "shit!". He immediately marched out of the office, leaving her sitting alone in her chair in shock. She was just about to get up and find out where he had gone when he reappeared in sweats and a t-shirt and raised his eyebrows at her questioningly. She smiled and bounced down to the gym after him.

They hit things, and each other, until he was feeling calmer. Once he was exhausted he sat on the edge of a large and complicated looking weight machine and talked his way through his problem. Natasha still had plenty of energy left so while he talked she danced – or rather she invented a silly combination of formal ballet, gymnastics and her particular form of martial arts. Every now and then a spin or a series of flips would render Bruce speechless, but when she stopped and looked at him questioningly he would dive back into his chemical combinations and newly discovered elements.

Over an hour later he seemed to have some to some sort of tentative conclusion and she was feeling her workout a little. She flipped her way back over to the edge of the gym, landing on her feet right in front of the scientist.

"You are disturbingly agile," he said, a little in awe.

"Well thank god I'm a super spy then, I'd make a terrible accountant. How about you Mr. Disturbingly Smart? Got it all figured out?"

"Hmm? Oh yeah, I think I have some ideas..but I'll have to-"

She cut him off before he could dive back in. "Go shower. I'll see you at the lab later. Takeout tonight?"

"Sure," he mumbled, but she could tell he wasn't really listening. his mind back in his lab. She ordered Chinese through JARVIS – a favourite of them both – and, when he adamantly refused to eat in his sterile lab, met him in the kitchen for a quiet dinner. He brought a tablet and pages and kept drawing things and then poking at screens on the tablet and looking excited.

She gave him the occasional encouraging smile, but mostly just let his voice wash over her, stuffing noodles in her mouth. She was feeling unusually sleepy, the comfy clothes she'd changed in after her shower not helping at keeping her awake. Eventually she decided to just give in and left Bruce to his test tubes while she curled into her bed, noticing with caution that it was very much starting to feel like her bed.

XXX

The buzzing on her wrist rocketed her out of sleep faster than the most irritating alarm clock ever could. She had her feet in her shoes, her tac belt on, and was out the door and in the hall before the third long buzz had even finished. Her mind sped ahead of her, down the hall and around the corner, picturing the Hulk tearing through the walls. She strained her ears for his roar, something breaking, a scream, but the hallways were quiet save for her frantic footfalls.

At last she reached Bruce's door and quietly gave JARVIS the cue to slide it open. Gun drawn, heart in her throat she stepped around the corner.

When a very alive and non-green Bruce met her eyes she let out a breath she hadn't realized she'd been holding. He had one hand up in an "it's okay" gesture and the other pressed hard against the bed where he sat.

"I'm fine," he said, before she could ask, her eyes scanning the room for danger, her gun still at the ready. "It was nothing, it was, ah, a mistake. It was a night- I was just...dreaming."

Relieved that the room was clear, Natasha tucked her gun back in its holster and crouched in front of Bruce. He was breathing heavily and his heart was pounding, a sheen of sweat across his forehead but he seemed under control.

"A dream?" she echoed, getting him to finally tip his head back and look at her. Another relieved breath came out at the sight of two brown eyes, crinkled with stress, but clear and present.

"Yeah, um. I'm sorry, it was stupid. I was having- I was dreaming and I woke up thinking I was, you know, that, The Other Guy was on his way and I panicked so, I uh, I pushed the panic button." He held it up as if in explanation and she couldn't help but laugh a little in relief.

"Don't be sorry, Doc. That's what it's there for. You push it, I come. I'd rather have a hundred false alarms than have you not push it when something's really happening." She turned to sit next to him on the bed. The cool silence of the summer night and the dim lights made her feel bolder than usual and she rested two calming fingers on the pulse point on the inside of his wrist, like she had so many weeks ago in his lab, until his heart rate slowed and he seemed to have shaken off the dream.

"So..." She wanted to ask how often he had dreams like that, but didn't want to freak him out. "How often should I expect these nighttime button pushes?"

"Oh, I uh, hopefully not again." Bruce pushed his hair back and stood up, turning away from her to grab a glass of water. Her fingers slid off his arm as he stood. "Usually I don't wake up...in the middle...like that."

His voice was flat, but there was something open in it she didn't get to hear very often.

"You dream about it a lot?" she asked gently.

"Yeah."

"Me too," she said plainly. His eyes shot up to hers, the pain and worry that haunted most of his looks back in full force.

"You-"

"No, no," she said, knowing he was thinking about the Helicarrier. "I mean, yeah, sometimes, but that's fair, right? No, mostly just that you're changing and I can't get to you in time."

Bruce paused, looking at her, his fingers gripping and turning the water glass, around and around. She saw a flicker of many conflicted emotions pass across his eyes. After a moment he sighed and gave her a soft smile. "I thought you weren't afraid of anything."

She shrugged. She was afraid. Terrified – of the Big Guy, yes but even more terrified of not getting there in time. "I don't like to fail. My job has been to make people talk, to make them believe something, or do something. More often than not it's to make them dead; sometimes to keep them alive. Keeping you yourself turns out to be a lot more complicated than all of those things put together."

"Sorry."

"Don't be."

Bruce moved as if to sit next to her again, but seemed to suddenly notice that she was only wearing a nightie under her tac belt and leaned back against the dresser awkwardly instead, a slight flush creeping up the back of his neck. They just sat for a moment in silence.

Finally, Natasha shook her head a little, clearing the rest of the sleep from her mind, and stood. "You okay?" she asked again, reaching out to touch his arm again. She felt stupid needing to know how he'd react to her touch, but the thought that he'd pull away again, was chewing her up. He didn't.

"Yeah." He gave her a glancing smile she'd started to dub his 'drive-by smile' in her head, looking back down at his hands, but not flinching or moving away.

"Ok. Goodnight, Bruce." She drew her hand back of her own accord, relieved that he was okay with her nearness and turned to go.

"Goodnight, Natasha."