Bruce, Tony and Steve drink coffee in the small private kitchen of what Steve calls the Avengers' Tower, Bruce is starting to think of as home and Tony knows is a testament to his genius.

"Where are Natasha and Legolas?" Tony wonders out loud.

"I don't know," Steve replies, half of his attention on Tony, half on his newspaper.

"I wonder what they're doing right now…" Tony leers.

"I'm sure they're just very good friends," Steve says firmly.

Natasha had been dating Ben, a linguistics professor with a handsome smile, for three months. He invited her to a museum opening and told her to bring a friend. She RSVP'd for Clint and herself, but didn't realize the not-too-bright leader of a drug cartel would complicate their plans.

"Jesus Tasha, did you have to break both his legs? We still have time," Clint said.

"Less talk, more driving," Natasha urged.

They sped down the highway, Clint at the wheel and Natasha in the backseat as she changed from her bodysuit to an evening gown. They ignored the muffled screams coming from the trunk of the car. Clint's phone rang. He made a face at the caller ID, but picked up anyway. He listened for a moment, expression pained at the voice on the other end.

"Yes sir," he said, and hung up. "That was Coulson," he threw back over his shoulder. "He wants us to come in and complete the paperwork for that guy." He jerked his thumb at the trunk. "And he didn't sound too happy."

Natasha almost snarled. "We're going to be late."

As predicted, the two agents arrived forty minutes late to the party. Moments later Clint was at the open bar. Natasha's Ben slid onto the stool next to him.

"Natasha tells me you're her best friend."

Clint nodded coolly.

"Are you going to threaten me? Tell me if I break her heart you'll break my arm?"

Clint laughed. "Nat can take care of herself."

Ben looked Clint up and down, sizing up a potential rival. Clint kept his eyes on his glass, sipping slowly. The bartender delivered Ben his drink. After a moment, Ben nodded to Clint and moved on to greet a colleague. Halfway through the evening Coulson called Clint with news of an escaped telekinetic terrorist. Clint handled it, because that's what friends are for.

Steve thinks of men long dead and battles decades ago, about friendships that are eternal even if the men who made them are not.

Bruce chimes in with his habitual nervous half-laugh. "They're spies. They could be secretly married for all we know. Besides, it's none of our business." Bruce fiddles with his glasses as he talks.

The only time Natasha isn't playing a role for someone is when she's sleeping. The first night they spent together she stole all the blankets and wrapped herself in a mini-fortress. She woke at small sounds and the slightest movement. But Clint was nothing if not patient, so he waited. It took six months of Tasha evaluating him for signs of betrayal or manipulation before she had a full night's sleep, before she slept with her skin next to his.

When he tried to tell her that he loved her she put a finger to his lips.

"Love is for children."

They still shared missions and a bed. Coulson assigned them to pose as newlyweds in a suburban community suspected of building killer robots. Natasha and Clint made a very believable couple.

Two weeks into their mission Natasha stormed back from a gossipy book club meeting. Clint greeted her with a kiss.

"Hill and Thompson are assigned to Paris and we're stuck in this suburban hell!" she exclaimed as the door closed behind her.

"It's not so bad-" Clint said.

"If we get married I'm never making you dinner," she told him bluntly. "Or ironing your clothes. And we're definitely going to have sex more than once a month."

Clint turned his choke into a cough. "I thought love was for children."

Natasha paused for a moment. "Then I am a child."

Natasha insisted on getting married under fake names. Clint insisted on rings. Coulson insisted on attending, and called their attempts at hiding their upcoming marriage from him "adorable."

Bruce remembers a partnership forged of equations and whiteboards, no less real than one formed from blood and bullets.

Tony looks thoughtful for a second. "I think it took years for them to realize they're perfect for each other."

Their second mission wrapped up two days early, leaving Clint and Natasha with a short vacation in Venice.

Natasha's inability to manipulate Clint worried her. That mission, she found a key. Natasha felt Clint's eyes on her as she worked the room; his obvious admiration was a weakness she could use. After the target was tragically drowned and safely on the way to the morgue she knocked on Clint's door, a bottle of vodka and two glasses in her hands.

He opened his door and she smiled demurely.

"Celebration drink?" she offered.

Clint opened his door wider to let her in. She was still dressed in the slinky green dress she wore for the mission and walked towards him with a sway to her hips. Clint was wearing jeans and a T-shirt that hugged his musculature. She ran her eyes over his body. This might even be fun.

They were pleasantly tipsy when Natasha made her move.

"Why Agent Barton, I do believe we're wearing too many clothes," she said, leaning forward.

"Nat, no," he said and forced himself to back away.

"Why?" she asked flirtatiously with a tilt to her head.

"Because you're pulling the same routine on me you pulled five hours ago. It didn't end so well for the other guy."

She stared at him open mouthed, trying to remember the last time she miscalculated so badly.

"Because we're partners. Friends even. You don't need to sleep with me for me to have your back," the words tumbled out.

Four years later she sat next to him in a small room on the helicarrier he helped damage.

"I've been compromised," she told him softly.

The words echoed around his head. He put his hand next to her cheek and their gazes locked. Years of partnership made spoken communication superfluous. He tried anyway.

"Nat," he started, then kissed her.

What began as a soft kiss quickly deepened. Natasha wrapped her legs around him and twisted to straddle him before breaking the kiss.

"What are you doing?" she asked, heart pounding.

He gave her a slow dangerous smile that sent heat through her body and reached for the zipper at the front of her suit. "Seducing you," he answered.

Tony thinks of partnerships that turn into love, of high heels and strawberry blonde hair.

"Bruce is right," Natasha says from the doorway.

Tony jumps, spilling half of his coffee on his Avengers T-shirt. "You're secretly married?"

"No, he was right when he said it isn't any of your business," Natasha says with a dangerous glare, moving agilely around the kitchen.

"You're no fun," Tony complains.

Unmoved, Natasha walks out with two cups of coffee in her hands.