A/N: Originally, I intended for this to be a oneshot. Then I got to the end and realized that my so-called oneshot was about 17,000 words and 37 pages long. Since I don't really feel like posting another monster fic, I've decided to split the story into five parts. Each new part will be posted every other day as I edit them.

I hope you all enjoy reading it as much as I enjoyed writing it. It's my first ever threesome fic, so it goes without saying I'm pretty excited.

Jane Foster had a certain routine. She liked to start each new day with a hot cup of coffee (or five), a fluffy breakfast roll, and a stack of new data to comb over while she ate. After that, it was down to the lab for another day of research and closing in on the answer to creating Earth's bifrost. As long as she stuck to that very simple schedule, she'd have a few hours in the evening to cozy up and read until her eyes grew too heavy and the fire burnt out. Perfectly quiet and peaceful. That was how Jane liked it.

Lately, she'd been able to pull it off without a hitch. Days when she couldn't usually started with an accident. If not that, then a crisis involving supervillains that required all civilian residents of the tower to hide on the basement levels until the Avengers had sorted it out. Sometimes, it was both.

Today, it was neither.

Today, Jane lost roughly ninety percent of her coveted breakfast research time—which also meant the loss of her equally coveted reading time—because of a battery.

More specifically, the uncharged battery of her cell phone that she was supposed to plug in to charge overnight. Otherwise, the damn thing would die on her while she was sound asleep and not blast a jaunty horn number in the morning to rouse her into wakefulness.

And so, Jane rolled out of bed more than an hour later than she should have, scrambled to get dressed and out of her apartment, and got nothing but rug burn and burnt toast for her troubles.

By the time she got to her lab, Jane's mood could not have been worse. She threw open the windows to let the light stream in and turned on some music, a fair attempt to counter her frustration. The music was a habit she'd picked up from Tony. Having worked in fairly close quarters with him for the past few months, it was only natural that she'd learn a few things, and that some of those things wouldn't be all that science related.

Unlike Tony, whose iTunes library consisted entirely of heavy metal and classic rock, Jane preferred something slower and more soothing for her work time. Pounding drums and shredding guitars would only shatter her concentration, but orchestral strings and echoing vocals gave her the same kind of peace she got from listening to the crickets and the howling coyotes back in Puente Antiguo. The sun was warm on her skin and the eatheral music eased her frustrations, and Jane could say that she was over her mess of a morning and ready to go on with the day as normal.

Then the door opened.

"Oh, Jaaaaane~!"

Jane dropped her notebook back onto the desk and closed out her windows. Now the work day was really over.

"Morning, Darcy," she said. "I thought I gave you the week off."

"Aren't I technically not your official intern anymore?" Darcy countered, making her way to her usual workspace next to Jane. "I got my credits in over a year ago. I'm here now because I want to be, and because I'm afraid that if I'm ever not here, you'll start jumping through portals to Mars or trying to establish contact with hostile alien forces or something crazy like that."

Jane shot her a look, but found she had no energy to respond verbally and left it at that. She returned to her computer, watching it spit out data while she doodled circles onto a sheet of notebook paper. Any second now, Darcy would say the one thing Jane did not want to hear.

Any second now…

"So what are you doing later tonight?"

And there it is.

"I'll be working all night," Jane said, making a show of typing some gibberish into her laptop. "I've got a lot to catch up on."

"I doubt that," Darcy snorted. "No offense, Jane, but ever since you and Thor split, you've been kind of a workaholic. Like more than usual, I mean."

"Darcy, I'm trying to create an Einstein-Rosen bridge," Jane said. "I'm working mainly by myself, and I'm more or less starting from scratch. I don't have time to fool around going to clubs or whatever it is you want me to do."

"Technically, it's not a club, it's a bar," Darcy said, as if that was supposed to make it better, "and there are always a ton of hot singles hanging around."

"I'm not interested."

"Well, even if you don't find someone to go home with, I might. Come on, Jane, I need my wingman!"

"So go ask Pepper or Natasha to go with you."

"I can't do that. For three reasons." Darcy held up one hand and proceeded to tick each one off. "One: they scare me. Two: I'm not on first name basis with them like you apparently are. Three: You are my best friend, and I want you to go out and have fun and stop moping around over Mr. Golden God of Biceps just because he likes warrior chicks better than science chicks. Who cares? There are plenty of other fish in the sea, and some of them are literally superheroes. You could bag one if you just put yourself out there."

"Darcy, I-" Jane started to stand, only to get tangled in a loose wire. She struggled with it for a moment, while Darcy looked on, raising an eyebrow. It finally came undone, and Jane kicked it aside. That was the third time in a week. "I get that you're trying to help, but I'm fine, Darcy. Thor and I broke up months ago. It'd be pretty pathetic if I was still hung up on him half a year later."

"And yet you're in this lab every night."

"Working in this lab every night," Jane shot back. "And what has it gotten me? Oh yeah, unlimited funding and a shot at the Nobel Prize. I think that's a bit more impressive than a boyfriend would be."

"I never said anything about impressing people." Darcy leaned back in her swivel chair. "Besides, what good is all of the success if you have no one to share it with?"

Jane let out a long, loud, exhausted sigh. She was starting to think she should say yes just to get Darcy off her back so she could return to her work. That wouldn't be good, though. She'd have to struggle for an excuse to bow out later, and Darcy would give her hell for it if Jane was too transparent. That, or she'd come up with a plan B.

"How about this? We forget the bar, and instead, I get you the info on one of those mixer parties for people with soulmarks. I hear there are even ones specifically for people in triad relationships."

Jane's eye began to twitch. That was always Darcy's plan B.

"I don't know if that's a good idea…"

"Oh, what's the problem now?" Darcy cried. "I mean, I get your objections to the bar, but having a soulmate pretty much guarantees you a successful romance. You've got two of them. That means double the romance and double the success!"

"Or double the work," Jane said. "Double the fighting; double the heartbreak if it doesn't work out. I know you think soulmates are romantic, Darcy, but that's only because you don't have one. Just because you do doesn't mean you're going to live happily ever after."

"Weren't your parent's soulmates?"

"Yes, and they fought just as much as any non-soulmate couple would. About all the same things, too."

"But they were happy together, weren't they?" Darcy got up and started to walk. "I bet their fights ended in hugs or make-up sex. My parents weren't soulmates. Their fights ended in divorce. If you've got a shot at avoiding that, then you owe it to yourself to take it."

"Darcy, even if I was actively searching, the odds of finding not one, but two soulmates are so low that it's not even worth pursuing. Why do you think there are so few completed triads out there?"

"Because everyone has the same ultra-negative 'I can't' attitude as you?"

"Okay, I going to go get some lunch."

Jane left Darcy to stick her tongue out at her and loudly lament at what a 'Negative Nancy' her boss could be. She entered the long, winding halls of the tower where hundreds of people walked every day. In the months since moving in, Jane never saw the same face twice, and with soulmarks on the brain, she couldn't help but wonder how many of them had words stamped somewhere on their bodies. How many had found their soulmate already? How many were even looking? How many would never find them at all or came so close to meeting the right person once, only for fate to decide it wasn't meant to be after all?

The best part was that this was going to be on Jane's mind for the rest of the day now.

Perfect.

When Jane was a little girl, her mother used to joke that her two soulmarks were placed on either of her hips so that she'd have room for both of them to hold her at night. It wasn't a very funny joke, or even one that made sense—they could still do that if her marks were somewhere else—but back then, it had made the starry-eyed five year old happier than she'd ever been. She'd go to sleep at night and dream about being a princess with two handsome knights leading her through a field of flowers, which they would lay in together while she told them all about the stars and what she read in her father's books. Long after she'd grown out of princess fantasies, that dream would still come every now and then, all the way up to her college years. By then, Jane was mature and practical enough not to base her romantic future on whether or not some guy said the words on her hip.

She was even ready to get married once, and live a happy, monogamous life with one man who respected her and cared for her. Then Donald Blake took her to a fancy five star restaurant for their two year anniversary, and the waitress said the words written on Don's forearm. That was the end of that.

Now that she'd failed once again to find lasting love, and with an actual prince no less, Jane was thinking she had better take a step back from relationships and focus on her work more. Her work, at least could never leave her (obtrusive bureaucratic government agencies or no). That was why she never bothered to go out with Darcy, or attend one of those soulmate finding parties. The way she saw it, if she happened to find one or both of them, then great. If not, then oh well. That's just how life goes sometimes.

Maybe it wasn't such a bad thing.

"In trouble again?" Jane asked as Tony Stark shuffled into the lounge with a pillow, a blanket, and a gloomy disposition.

"I told Pepper I didn't want to go to her mother's birthday party," he said, flopping down on the couch with his eyes on the ceiling. "I don't get it. The woman hates me. Pepper knows that she hates me, and yet she still insists that I go and spend time with her three or four times a year. I send her a new luxury car every Christmas. That should be enough."

"Maybe she wants you and her mother to get along," Jane suggested. "Like beyond the whole luxury car thing."

"If that was a possibility, it would have happened by now," Tony said. "I've known Pepper for fifteen years, been dating her for three, and if in that time, Mrs. Potts can't accept the fact that I'm Pepper's soulmate and I'm not going anywhere, there's nothing I can do about it. Except maybe buy her a plane."

Tony looked thoughtfully off into the distance, perhaps thinking of exactly how he could pull that one off. Knowing him, it wasn't likely to end with Pepper's mother warming up to him, and extremely likely to involve a lot of collateral damage to public property and Pepper frothing at the mouth with anger. As always when Tony got like this, Jane wisely kept it to herself.

She scooted over, making room for him to lay out his blanket on the couch. For a moment, Jane wondered why he'd be going to bed so early in the evening. Then she checked her phone and it was past two in the morning. Her body clock really was shot.

"By the way, have you seen Bruce around?" Jane asked. "I wanted to talk to him about some new research I've been doing, but I can't find him."

"You're not going to. He's on 'vacation' again. Even I don't know where he is or when he'll be back."

"Another spiritual journey?"

"Something like that." Tony shrugged. "Whatever helps him, I guess. I just hope he'll send a card this time. You want to know more, I'd ask Capsicle. I saw Bruce talking to him right before he left."

"I wouldn't know where to find him either," Jane said.

Tony blinked. "Oh yeah, you and Cap haven't been introduced yet, have you?"

"I haven't had much time to socialize lately. I don't think I've met even half the people who live here."

"Eh, I don't blame you. You are a big important scientist now, and Cap has been pretty busy with that boyfriend slash fellow Popsicle of his. I don't think I've had a proper conversation with him in a month; he's always running off with Barnes."

"Well, they are soulmates. You of all people should know how that is."

"I guess."

Tony turned onto his side, facing the cushions. He grumbled something about getting more comfortable furniture and fell asleep with Pepper's name on his lips. It was sweet, Jane thought. An hour from now, Pepper would find him in here, because she'd have gotten just as lonely lying in bed without him. Tony would wake up to find her curled up against him and tucked under his arm, and he'd be content to stay and watch her sleep for another hour or so before she finally stirred.

Over the past few months, Jane had seen the whole scene play out so many times that she knew it by heart. First they'd fight, then Tony would leave, then Pepper would miss him, then they would (loudly) make up. She didn't know if it was what she would call an ideal love, but it worked for Tony and Pepper. What they had was unique and uniquely theirs. Jane believed whole-heartedly that they would last forever, soulmate or no. Because in their own weird way, Tony Stark and Pepper Potts were simply perfect for each other. Soulmates in every sense of the word.

Steve Rogers and Bucky Barnes could only be the same way, if even better. Though Jane had never spoken to either of them, she had seen them from afar. They were hard to miss, both large and broad and always together. Whenever Captain Rogers was talking, Barnes' eyes never strayed away from him, and if something triggered Barnes' memories of being held captive, Rogers was there without fail, holding Barnes close and telling him over and over again that he was safe now; it would be okay. Between that, they could be found training together, eating together, or just trading jabs and playful insults. The few times Jane bore witness to it, it had brought a nice little smile to her face. There was a couple to aspire towards for sure. If Jane could ever find someone who would love her like those two loved each other, she'd be a lucky woman.

In a better world, that might have been Thor…

But no, no use lingering on that old relic of the past. She and Thor had agreed that so much time apart and so little time together had killed the passion between them, and that they worked better as just good friends anyway. It had been mutual, amicable, and left both parties satisfied and without regrets. Thor would always have a place in Jane's heart for making her dreams come true, and she would be the one who helped him become a better man.

He and Sif made a beautiful couple anyway. They looked so happy all the time. Happy like Tony and Pepper and Rogers and Barnes were happy. What was it like to be so happy, Jane wondered.

Leaving Tony to dream and await Pepper's arrival (by her count, it would be another twenty minutes), Jane exited the lounge and entered the hall that lead to the elevators. The normally busy halls were close to deserted this late at night, but signs of life did remain. A janitor was making rounds through the labs and meeting rooms, tossing all garbage into a big black bag. A few of the live in technicians were performing routine maintenance, and one of the Avengers' new team members—Sam Wilson, if Jane remembered correctly—was just leaving the gymnasium. He gave her a smile and a nod as he passed, both of which Jane shyly returned.

The elevators were right behind a large metal door that prevented anyone without authorization from getting in or out. Jane scanned her ID card and awaited the solid green light that would grant her access. The door slid open. Jane took one step before her eyes adjusted to the dimmer light and-

'Oh my god. Oh my god. Oh. My. God.'

Steve Rogers.

Steve Rogers was pressed up against the wall between cars four and five, covered in sweat with his shirt buttons undone.

Bucky Barnes.

Bucky Barnes was holding Rogers' arms above his head while sucking a spot on his neck and fingering his pants zipper.

Steve Rogers and Bucky Barnes, legendary soulmates, war heroes, and Avengers, were getting it on right in front of her.

Just like that, Jane's night had gone from average mundane to something out of a softcore porn flick, and at the rate they were going, it wasn't going to stay soft for much longer.

Jane's mouth fell open. She wanted to speak or squeak or scream, or maybe she didn't. Either way, her voice was gone. The only way she could have let them know they weren't alone would be if she made some kind of sound that her normal ears could never hear, but that their super enhanced hearing could pick up from a mile away.

All of a sudden, Barnes was moving off of Rogers, his piercing blue eyes going through Jane like bullets from a gun. The two men stared at her, one with embarrassment and one with annoyance. Once again, Jane thought about speaking, explaining that she hadn't meant to interrupt them, she just wanted to get upstairs to her room and go to sleep, minding her own business about whatever it was they got up to. She just couldn't get her mouth to move, no matter how hard she tried.

That was when Barnes spoke first.

And the words he said, Jane'd had them memorized since she was a child.

"Ever heard of knocking?"

Something heavy fell down on Jane's shoulders. That was how she felt, weighed down by the force of what had just happened and what it could mean.

No, that wasn't the question. Jane knew exactly what this was, she just couldn't believe it. The rational part of her brain said that it had to be a coincidence. That was a perfectly common thing to say in response to this type of situation, and just because she had those exact words written on her left side didn't necessarily mean that anyone who said them to her was automatically one of her soulmates.

If that was true, then Captain Rogers…

Captain Rogers…

Captain Rogers hadn't spoken to her yet. He was too busy staring at Barnes.

"Buck, don't be rude," he said. "We knew there was a chance we could get caught doing this."

He turned to Jane, who sucked in a breath. This was the moment of truth. It was very rare that Jane Foster prayed, but she did now. She prayed that the next words out of his mouth would be anything (anything at all) except-

"I'm sorry if we scared you, Dr. Foster. It won't happen again."

'OH MY GOOOOOD!'

In retrospect, Jane thought she had a perfectly reasonable response to the discovery that Captain America and the Winter Soldier were her soulmates.

She turned right around and ran like the wind. She took the stairs up ten flights to her floor and didn't lose energy until long after her body hit the mattress.