A/N: Almost as soon as I finished 'Buck to the Future' I started getting the urge to write a sequel, but I was happily busy with other fics and RL stuff for a while there, and also, I wasn't 100% set on what the setting or plot of said sequel would be. Now, I have it figured out and I have time to dedicate to all the actual writing, editing, etc. that's needed to get it done, so here we go...

Disclaimer: All recognisable characters, situations, and dialogue from any film or TV series in the MCU belongs to Marvel and other folks who aren't me.

Chapter 1 - 15th/16th November 2013

Every time Bucky Barnes thought he knew everything he ever needed to know about Natasha Romanov, she surprised him all over again. Not that he minded at all. From the beginning, she had sparked his interest, even before he knew she was an Agent of SHIELD, when he thought she was a life-saving nurse, rather than capable of taking the lives of any bad guys that came along. When the revelation came, the day Bucky and Steve were recruited into the Avengers Initiative, he didn't think he could be more surprised, he wasn't even sure he could adjust and accept who Natasha really was, but he was wrong.

It was strange to think he had been in the modern world for more than two years now, and that he and Natasha had been in some kind of undefined relationship for almost eighteen months of that time. Not that they saw each other all that regularly. She had her missions, he had his, not to mention all the training he went through, and the down-time they spent apart. Still, they always seemed to circle back to each other at some point, and almost every time they met up again, she found some new way to surprise him. Today was no different.

When he got back from visiting with Steve in Washington DC, the first thing he asked JARVIS on returning to his apartment in Stark Tower was if Nat was around. He was directed to the fitness level where he searched a row of side rooms, until suddenly he saw her through a small window, red hair flying as she spun around and around.

Bucky had seen her fight, so many times. For training's sake, and sometimes just for fun, they sparred together. He knew how she moved, how fluid and flexible she was, and not just for fighting, but this was the first time he had ever seen her dance ballet.

She was incredible, beautiful, and completely hypnotising. Of course, Bucky had applied all these adjectives to Natasha before, but this still felt different. Like he was seeing one more facet of her personality, one more piece of her past maybe. Perhaps she would tell him later, perhaps not. It didn't matter. They talked about a lot of things they never spoke to anyone else about. There was a strange amount of trust between them, proven in this moment, Bucky supposed.

Though he let himself in, watching her from the corner of the room, she didn't lose a step or a beat, pirouetting and leaping like a true professional. Natasha knew he was there, she always knew, she was just certain she was perfectly safe with Bucky watching her. God only knew what drew them together or told them they were each safe in the other's company, no matter what, but that feeling was always there.

As Natasha's silent performance came to a sweeping end, Bucky applauded her skill, glad to see her smiling as she rose back to her feet.

"I didn't know you were back."

"I just got in," Bucky told her, kicking off his shoes before he approached her across the polished floor. "I didn't know you could dance like that."

"There's still a lot you don't know about me," she countered, a smirk pulling at her lips then as her eyes moved down his body and back up. "But dancing has a lot in common with fighting. It's all about learning the steps, keeping to a rhythm..." she explained, shifting to a battle-ready stance.

Bucky knew the drill, taking up a similar pose, moving in for an attack that he knew she would easily counter. They ran through the same routines to start off with, warming up, getting into the zone. After a while, things got a little rougher, a little more surprising, but then, that was usually half the fun. He got the upper hand, then she did, the fake battle going back and forth, on and on. As she escaped his latest hold, she was grinning at him from a few feet away, barely even breaking a sweat, despite all the dancing followed by the fighting.

"You know, Fury asked after you just yesterday."

"About my general health or...?" Bucky asked, trailing off as they circled each other still.

"The progression of your skills in relation to your ongoing training with SHIELD."

"And what did you tell him?" asked Bucky curiously, sure he could be certain of some clever answer or other.

"That you're a fast learner," Natasha said honestly, before the smirk returned to her lips, and she came at him one more time, "that your knife skills are still a little sloppy," she said teasingly, and Bucky knew it, since the last time they trained together he had repeatedly dropped the fake knife she was trying to teach him to flip, "but I never could fault you on your hand-to-hand," she continued, as he grabbed at her, spun her until her back was against his chest, "or your holds," she added, pressing herself more tightly against him, surrendering to his grip as far as Bucky could tell.

She could get away and they both knew it, she just didn't want to anymore. He was more than okay with that. "Anything else?" he asked, holding her tight, beginning to lose concentration as she very deliberately moved her body against his own.

"Yes," she said softly, suddenly turning on him - before Bucky knew what was happening, he was flat on his back on the solid floor with Natasha on top of him. "You're a little too easily distracted," she said, triumph in her face and her voice.

"Only by you, doll," he insisted, smiling as he reached up to pull her head down until she was close enough to kiss.

She went willingly, falling into him, the two of them quite literally rolling around on the floor like teenagers. It was nice to be that way, to feel able to be young and foolish. Given all the horrors they had seen in their lives so far - him in the war and more recently with the Avengers, her in the dark past she rarely spoke of and since on certain SHIELD missions - it was no bad thing to get the chance to act innocent and free once in a while, even if it never lasted long.

"You know," she said when they finally let each other breathe for a minute, "if anybody else called me doll, I'd probably inflict some serious damage. How do you make it sound so much less patronising than every other guy?"

"Because I've never meant it in a bad way any time that I've said it," he said, shrugging his shoulders as they lay side by side on the floor, both propped up on an elbow facing each other. "Not back then and not now with you either. It's just... I don't know, a term of endearment, I guess."

"Well, I don't hate it," Natasha admitted, smiling as she reached out to mess with his hair. "This is different, but I like it."

"I know that you do," he replied, leaning into her touch as her fingers moved around his neck.

He felt strange about telling her that part of the reason he hadn't had his hair cut in the last few months was exactly because she said she liked the idea of it getting longer and thought he might look good that way. 'Not that you're not cute enough already, obviously,' she had insisted with a smile, similar to the one she was wearing right now.

"You don't exactly look terrible with the longer hair yourself," he said of her flame-red locks that now reached her shoulders.

"Really? 'Cause I was considering going shorter, really short, maybe blonde too."

He wasn't sure if she was kidding. No matter how much he thought he knew her, that he could read her, there were times when she still seemed to be one step ahead.

"You know I'm kidding, right?" she checked then, leaning in closer and kissing his cheek. "I think I'll save that for if I ever need to really disappear"

Bucky hoped that was a part of the joke too. The idea of her going away and never coming back pulled at his heart in a way he didn't know how to express. Of course, they were apart a lot. She went out on missions and so did he. Other times, they just had other places to go and other people to see, and that was fine. Bucky supposed it was okay because he knew she was always coming back. Even the most dangerous, classified missions, he never failed to believe her when she said she would see him again soon, and was sure she must know he meant it when he said the same. They fought to stay alive because SHIELD and the Avengers and the world needed them too, but on his part at least, Bucky knew he was always fighting to come back to Natasha too. He wouldn't ever ask her if the same applied for her, even though he was tempted sometimes.

"What's that expression for?" she asked then, studying him closely. "Is this hard floor a little much for an old man's bones?" she teased, playfully kicking him.

"Honestly? I can think of more comfortable places to... lie down," he said pointedly.

Natasha rolled her eyes at the terribly pointed comment, but her smile remained as she got up on her feet in one fluid movement and reached down to offer him a hand up. Bucky didn't need the help, but took it anyway, glad of her hand wrapped around his own, happy when she didn't try to pull away the moment he was standing. They went to the elevator like that, hand in hand like teenagers in love, even though they were far removed from such a thing. That much they proved after they travelled up a few floors and entered his apartment, the passion that had sparked between them reigniting once again all too easily. Innocent children they were not, as they fell into his bed together, reacquainting themselves with each other in all the best ways.

From there, it became a long lazy afternoon and evening of talking and fooling around, catching up with each other and depleting the supply of snack food piled high in Bucky's kitchen cabinets.

"You know, I should be mad at you," she said in a quiet moment, the two of them laid in bed together, half-watching some badly-dubbed Korean soap opera on the TV. "Thanks to your super-soldier serum, you eat like a twelve-year-old and you're built like this," said Natasha, her hand running over his chest and abs. "I'm going to spend hours in the gym working this stuff off." She sighed, shoving the large bag of chips further away.

"Oh, yeah, you're really in terrible shape." Bucky deadpanned, rolling his eyes at her words. "I highly doubt one afternoon of indulging is going to make that much of a difference to this figure," he said, tickling her ribs until she squirmed.

"Hmm, you're a bad influence, James Barnes," she said then, meaning more than just the food he was sure, as she shifted her body further on top of his own. "Given the kind of guy you are and when you come from, I didn't really see that coming," she told him, stealing one more kiss. "But it's getting late, I should probably head out."

"You sure about that?" he checked, holding her tighter when she started to move away, kissing her once, twice, until he felt her give in to temptation.

The TV was forgotten and the snacks abandoned to the point of tipping off the bed and no doubt making a mess, not that Bucky or Natasha would have noticed at the time. As they took their pleasure of each other all over again, the hour grew later still. The clock on the nightstand blinked 11:57, practically midnight, the lights in the room having automatically dimmed as they were set to do when the hour grew so late.

"I really should go." Natasha sighed from within the circle of his arms.

"Why?" he asked, as he had what felt like a million times before, kissing the top of her head. "You know you can stay here. What difference would it make?"

She never gave him a real reason, only excuses, but for as long as this thing between them had been going on, Natasha had never once slept with Bucky. They had sex, got up to all kinds of things, but she refused to fall asleep in his bed, and any time he woke up in hers, she was never there, never seemed like she had a wink of sleep herself.

"I just need to go," she repeated, a yawn almost taking the last couple of words away entirely, and for once, she did seem reluctant to follow through on the action.

"Natalia," he said softly, her real name that so few knew and that he only ever used in quiet moments in the dark like this. "You don't have to go. You trust me, don't you?"

Lifting her head to gaze up at him through her lashes, he could just about make out her slight smile in the darkness. "James, you know I do."

"Then stay," he urged her. "Why not just stay?"

He wasn't even sure why it mattered so much to him, but it did. The idea of her lying beside him all night, the thought of waking up in the morning to her head on the pillow next to his, it all appealed so much. If she trusted him, as she said she did, as she proved in a hundred different ways since they met two years ago, then why not?

"Okay," she whispered, nodding her head then. "I'll stay."

With a smile on his face a mile wide, Bucky pulled her ever closer, told her thank you, and settled down to sleep. After the exertion of all their physical activities, even the most super soldier or well-trained agent would need plenty of sleep. Bucky half-expected to be out for the count until at least mid-morning and knew neither of them didn't have to care if that was the case. Natasha was due a little down-time and, barring emergencies, nobody was really expecting him to be back and available for active duty until Monday. They could have the whole weekend, if they wanted, or so Bucky had thought.

He came to with a start, unsure what had woken him, glancing at the clock and finding it was a little past four in the morning. The bed beside him was empty and already cold. Calling out for Natasha, he wasn't overly surprised when she didn't answer, sure she had just changed her mind when it came to the crunch and headed back to her own place. He realised that couldn't be true when he saw her clothes still strewn on his floor.

Hopping out of bed, James went out into the living room to look for her, then tried the kitchen, before it finally occurred to him, she probably just slipped out to use the bathroom, yet when he got to the door, no light showed under it.

"Natasha?" he tried, tapping gently on said door. "Are you okay?"

The sound that came in response to that was like nothing he ever heard from her before. No words, nothing coherent, more like a strangled sob. Startled and concerned, he shoved open the door and found Natasha huddled in the tub, shaking horribly and looking genuinely scared.

"What happened?" he asked, moving closer, hating to see her flinch the moment he reached for her. "Natasha?"

"It's nothing" she said fast, still twitching and shaking. "I just... I had a nightmare, that's all."

It didn't make sense. Of course, everybody had bad dreams sometimes and woke up shaken from them. Bucky still got flashbacks to the war, to HYDRA's experiments and Red Skull's ugly grinning face. To the moment on the train high in the mountains where he almost lost his life, to bombs and gunfire, and a dozen near-misses that were nearer still when his mind was playing tricks on him in the night. He even dreamed of the Battle of New York sometimes, of things going differently, of losing Natasha and Steve and being alone. Those things scared him, and he was sure Natasha had a million ugly memories to be frightened of in the dark too, but this was more than that, it had to be. He never saw anyone as shaken up as she was in that moment. Up to this point, he had rarely seen her flinch at anything at all, and they had been in more life-and-death situations together in the last couple of years than most people would ever think to deal with in a lifetime or two.

Reaching for a towel, Bucky all but threw it over Natasha, afraid to even try to touch her again after her initial reaction. Crouching by the tub, he rested his arms on the edge and his chin on his hands.

"I'm sorry," he told her, shaking his head. "If I made it worse, busting in here like that. I just... I was worried and... Natasha, this isn't like you. I've never seen you scared like this..."

"Everybody gets scared," she told him sharply, though thankfully the shake was gone from her voice and her body seemed to have stopped jittering too. "But I'm sorry too. It's not your fault, it's just... My nightmares are a little too real, sometimes," she said, meaning his gaze with red-rimmed eyes. "Now do you see why I never sleep over?"

Bucky could have happily knocked himself out on the tile for being so stupid. Of course, it made sense that she didn't want him to see her this way. He wouldn't exactly love the idea of the situation being reversed either. Most people wouldn't want to look so vulnerable in front of anyone, especially people like them.

"I'm sorry," he told her again. "I didn't... What can I do?" he asked her helplessly.

"Nothing," she said, shaking her head and visibly swallowing hard. "I'll be fine, I just... I need my clothes and I need to go."

He didn't try to stop her, didn't argue, didn't cajole, not this time. Instead, Bucky only nodded and went to retrieve her clothes for her. When he got back to the bathroom door, she was already there waiting, wrapped in the towel and looking shaken yet. She muttered her thanks, grabbed her shirt and pants from his hands and disappeared back into the bathroom, emerging five minutes later and brushing past him as if she hardly noticed he was there.

"Natasha?" he called on realising she was headed straight for the door without a word.

"Just let me go, James," she urged him, sounding more frustrated than he had ever heard her before, at least when talking to him. Then she heaved a sigh and turned back around to face him. "I'm sorry, okay? It's not your fault, I just really need to go."

"I'm not stopping you," he told her, hands held up in surrender. "I just don't understand why a nightmare means you don't want to be near me."

She looked so sad as she stared across at him then, like there was something she wanted to say but couldn't, or perhaps just something she had to say but didn't want to at all.

"It's not about you. I... I know you think you know me, James, but you don't. Not really," she told him, shaking her head. "If you did then... things would be different."

"Then tell me," he urged her, daring to take one step forward, glad at least that she didn't back up anymore, though she didn't get any closer either. "Tell me what it is I don't know. It can't be that bad."

The strange smile that remark brought to her lips was not at all comforting, and then she turned on her heel and was gone before Bucky could hardly blink. He knew better than to follow her.

To Be Continued...