Summary: She and James had been together―whether as friends or as a couple―for so many years now, that it was hard for her to imagine them separated. He'd been with her since what felt like the beginning of time and sometimes she forgot that others didn't know just how much they'd lived through together.

A modern AU.

It was entirely Tony's fault they were celebrating her birthday, but after so many years of keeping the date a secret, it was kind of a nice change. She still wasn't exactly sure how Tony had figured out which day she'd been born, but if he was determined enough to search through what had to have been dozens of incomplete Russian hospital records, she could at least attend the party he threw for her.

A day that had once been filled with only muttered abuse from her stepfather was now, apparently, worthy of a Stark-funded party.

"We could tell him the records are wrong," James muttered, scowling as he watched her pick through her earrings. "Or that we already had plans. Which we did."

"Our plans can be moved for one year," Natasha told him, settling on a pair of diamond studs. "They haven't changed since we were sixteen anyway."

Since the first year she'd known James, her birthday had been reserved just for them. At ten years old, they started what would soon become a tradition: movies and ice cream in the dead of winter. Just like everything she'd done with him from the very first moment he introduced himself, the little tradition had become a lifeline that she clung to tighter than anything else (aside from James himself). At sixteen years old, the tradition had been extended to include a dinner where James had ever so shyly admitted to it being a date ("A real one. Not just cause it's your birthday.").

"Between the two of us," James teased, "I'm surprised you're the most okay with this."

Natasha glanced back at him, unsurprised to find him sitting on the edge of their bed with his shoulders slumped. He'd seemed more excited about her birthday this year than in the past, except for the time when he'd kissed her over the dinner table for the first time. She was trying not to read too far into it.

"It's how Tony shows affection: with his money." She joined James on the edge of the bed. "He's been trying to do this since our first year at NYU."

James snorted, remembering the many, many times Tony had bribed either one of them to tell him when Natasha's birthday was. Now, five years later, he'd finally found out.

"Even if we aren't going to a kitschy theatre or a hole-in-the-wall restaurant," Natasha murmured, "it'll still include the thing I look forward to the most." She reached for James's hand and, trying not to think about how goddamn cheesy she was going to be, said, "You."

"Wow, that was real smooth," James teased, squeezing her hand. "You work on that in the shower?"

With a roll of her eyes, Natasha let go of his hand and stood up. "After eight years of suffering through your romantic gestures, I've learned a thing or two."

James grinned.

"Now let's go," Natasha said, marching towards the door. "The sooner we get there, the sooner we can leave."

All it took was a wriggle of her brows and James was at her side, opening the door and ushering them both down the rickety flight of stairs to where Tony's driver was waiting to take them to the party.

* * * * *

She had known that a party thrown by Tony Stark would mean there were people there that she didn't know, but she hadn't accounted for all of them also bringing her presents. Tony had set up a table near the penthouse elevator where a large stack of gift bags, envelopes, and wrapped boxes was already awaiting her.

"Bozhe moi, Tony," Natasha muttered as they stepped out. Beside her, James snorted.

"If any of those envelopes contain cash," he whispered, "we're definitely returning to that restaurant Stark took us to last week."

Natasha nodded in agreement, eyeing the pile of gifts warily before stepping past it in search of Tony.

After swearing up and down that (almost) everyone in attendance was part of their NYU graduating class, Tony promised not to introduce her to anyone she didn't recognize on her own. They may have shared a few general classes, but after their third year at the school, Tony's classes had differed wildly from hers. She had a feeling that he'd invited more of his old friends than hers, but she spotted Steve Rogers already speaking with James and Clint Barton whispering conspiratorially with Maria Hill and Sam Wilson in the corner.

"They all know your name, at least," Tony promised, throwing an arm over her shoulder. "I made sure of it, Red."

"Well in that case," Natasha said drily, "we were surely best friends."

Tony didn't take her tone too seriously and, luckily for Natasha, kept to his word. Aside from the few people that approached them, Tony didn't take her around the entire room and make introductions to everyone who had apparently come to celebrate her birthday with her. It wasn't until Tony left to greet Pepper and get them both drinks that someone Natasha did know approached her.

"Natalia!"

She turned, fully expecting James despite how different his voice sounded. Since arriving in the States, she hasn't heard anyone other than him use that name.

"Alexei?" She frowned, uncertain if the dark-haired man that was quickly approaching her was indeed Alexei.

With a wide grin and a nod, Alexei pulled her to him and pressed three kisses to her cheeks. Although caught off guard, Natasha returned the gesture on sheer muscle memory.

"I hear it's your birthday," Alexei said in Russian and, despite herself, Natasha smiled at the sound of the language.

"Yes, that's what Tony's said, isn't it?"

It'd been over a year since she'd seen Alexei. During her time at NYU, he'd been a close friend as a fellow Russian student. They'd only shared one or two classes a year, but Natasha had been more than eager to make friends with someone who was also from her country and had moved to New York.

"I brought you something," Alexei told her. He pulled a small jewelry box from his pocket and Natasha took it from him curiously. "Open it," he encouraged.

When she peered into the box, she found a pair of earrings laying inside. They were made from a shimmering emerald and perfectly matched the forest green dress she was wearing.

"Oh my," she breathed, "they're beautiful, Alexei. Thank you so much."

Her eye caught James's across the room and, realizing she didn't have either pockets or a handbag, she lifted her chin in hopes he'd join her for a moment. As he excused himself from his conversation with Steve, Natasha turned back to Alexei to thank him again.

"You really shouldn't have," she told him, admiring the earrings. "I feel like they are worth more than just my thanks."

"It was truly nothing," Alexei assured her, "though if you joined me for dinner tomorrow evening, I would consider it thanks enough."

James slid up beside her, a drink in one hand and a warm smile.

"Alexei Shostakovich," he greeted in Russian, "it's been a while."

"Indeed."

Natasha frowned, not missing the way Alexei's voice hardened at James's approach. James seemed to blink right past it, excusing himself for interrupting before turning to Natasha.

"You needed me?" he asked, switching to English. Natasha nodded, passing him the jewelry box and reaching up to remove her current studs.

"I don't have pockets," she said as an explanation.

She could feel Alexei's eyes on her as she turned to James, replacing the diamonds in her ears for the emeralds in the box.

As James closed the jewelry box, he nodded towards the coat closet and said, "I'll go put this in my jacket."

"Thank you, my love," she murmured, bringing her hand up to cup his cheek for a brief moment. James's smile softened and he pressed a kiss to the inside of her wrist before slipping away to put the jewelry box away.

When Natasha turned back to Alexei, his smile had hardened.

"How long have you been with him?" He nodded after James.

"Eight years," Natasha answered. "Since we were sixteen."

Alexei's frown deepened. "You were together at New York University?"

At Natasha's nod, Alexei scowled.

"You never mentioned it," he muttered.

"I didn't realize I should have," Natasha told him, which was the whole truth.

She hadn't ever felt the need to tell others that she and James were together. He went with her wherever she went and had done so since they were ten. It had been so long since she'd gone without him that to her, they had always been together. She hadn't thought about her and James as being separate since well before they ever moved to the States.

Alexei merely grunted, glancing towards the bar to her right with a scowl.

"Happy birthday, Nastasya," he grumbled before sliding through the crowd towards the bar. By the time he'd seated himself on a stool, James had returned to her side.

"Alexei left?" he asked. His arm curled around her waist.

"Yeah," Natasha hummed, still frowning. "He didn't know we were together."

"Huh." James followed her gaze towards Alexei.

"Yeah. Huh," she echoed.

Moving his arm from her waist to her wrist, James tugged on her hand gently and stepped towards the dancefloor Tony had set up for the evening.

"Dance with me."

Natasha moved with him, letting him guide them both onto the dancefloor. She curled into him, content to sway with her arms around him for the rest of the night if she was allowed to. As cheesy as she had sounded earlier, her favorite part of their birthday tradition was the time spent with him and so far, she hadn't spent more than a few passing minutes with him.

"You seem to have warmed up to the party," Natasha murmured, pressing her lips to his ear.

"Steve talked some sense into me, I suppose." He squeezed her hip. "There are other nights to propose."

Natasha stood still in his arms, pulling back to cup his face between her hands.

"You were going to propose." She'd had her suspicions when James had first started grumbling about Tony ruining their night, but she hadn't thought he'd tell her as much.

"Don't sound so surprised now, doll," he teased, pressing a kiss to her nose.

"You weren't the best at hiding it," she teased in return. Her face softened. "I'm sorry Tony ruined your plans. Tonight would have been a wonderful night to propose."

"Oh, Tony will be paying for it," James assured her with a grin. "Quite literally, too."

Natasha rolled her eyes but couldn't keep the smile from her face.

"Whenever you do propose," she said softly, "I'm sure it will be perfect."

"It will be," he whispered, pulling her back to his chest with a brush of his lips to her brow. "Happy birthday, Natalia."

Even if they spent the rest of the evening swaying on the dancefloor, Natasha couldn't have imagined the night ending any better.