DISCLAIMER: I do not own the Avengers.

Constant

Natasha sat down on Clint's chair, her knees together and her back ramrod-straight.

"You're a spy, not a soldier," he said. She could feel him looking at her, but she kept her gaze locked on the window in front of them. "Now you want to wade into a war. Why? What did Loki do to you?"

"He didn't," she said. "I just…"

She just…what? Lost herself? Assassinated a few people? Developed a moral compass whose needle spun haphazardly between good and evil?

She had committed a lot of crimes of which she was ashamed, and she had to atone for them somehow. But Loki's voice, dripping with venom, slithered into her mind. Drakoff's daughter…Sao Paulo…the hospital file…gushing red…will never go away…

Clint placed a hand on her arm. She drew back, surprised that someone with his combination of brute strength and raw anger could be so gentle. "Natasha," he whispered.

Just that. Just her name, but he said it with a tenderness that lightened the weight of her lead-encased heart. This man was her best friend, the only person in the world that she could even begin to trust. And even though he'd been violated in the worst possible way, had his very mind stolen from him, he was sitting there next to her, worrying about her.

Natasha pushed Loki's rancorous voice out of her head and told Clint the truth. "I've been compromised," she said. "I got red in my ledger. I'd like to wipe it out." She kept her voice steady and monotone.

"Me too," he replied. "But we can never erase the red. We can only atone for it."

They sat like that for a few moments, side by side, shoulders and knees touching. And even though they remained silent, it was a companionable silence, not an awkward one. Natasha's shoulders relaxed a hair.

Her mind rewound the tape of their time together. Fighting back-to-back in the desert...Clint holding her hand in the ICU...those few hours they had spent in a Parisian cafe...attempting to use each other's weapons...and that first moment, back in Russia, when she had been looking down the barrel of his gun and he had decided not to follow orders.

Natasha turned her face towards his, locking his familiar blue eyes with her own. "You were my constant," she said. It was becoming more difficult to keep her voice under control, but she managed it. "I thought I had lost you."

"I'm sorry, Nat," he said. "I—"

"No, it's not your fault," she interrupted. "It's Loki's. That's why I'm going to hunt him down and snap his spine."

"Not if I get there first," Clint said, his eyes sparkling. He looked down, hesitating, and then took her hand. "Nat, I can still be your constant. You know that you're mine."

His hand was rough, but warm.

You may not get this chance again, said a small part of her mind. Do it now.

Natasha took a breath. Compared to Budapest, this would be easy.

In one swift movement, she swung her legs so she was straddling Clint's lap, her face inches from his. She cupped his cheek with her free hand and kissed him.

He stiffened for a moment—surprised, perhaps—but before long, he had moved his hands to her waist and was kissing her back. He tasted of blood and bile, the bitter remnants of battle. His muscles flexed beneath her.

It was without a question the most enjoyable part of her day.

By the time they stopped to catch their breath, she was lying on top of him on the chair and his vest was somewhere on the floor. A thin line of blood trickled from his lip. "You bit me," he said, touching it gingerly.

For the first time in a long time, Natasha smiled. "Today alone, I've kicked you in the groin, twisted your arm, slammed your head into a metal bar, and punched you out of consciousness, and you're complaining about a split lip?"

Clint laughed and squeezed her hand. "Thanks again for saving my life." His face transformed when he smiled, the furrows of concentration usually etched into his skin giving way to laugh lines.

"I owed you," she said.

"And this?" he asked, raising his eyebrows. "Was this part of my repayment as well?"

"Shut up," said Natasha, and kissed him again.

A dark and terrible urgency lurked behind their movements, fueling their passion but tingeing it with unease. Both of them knew that they might be called to fight at any moment—and not the straightforward, calculable fights they had trained for, but fights against magic and monsters and alien nonsense, things they couldn't imagine in the few spare minutes they had to dream.

They were not children playing at love. They had never been children. But they were falling, flailing, looking for something to hold onto as the rest of the world crumbled around them.

"You are my constant, Clint Barton," she said, tracing the bulging veins in his arms with a thin finger.

"And you are my constant, Natasha Romanoff," he replied.

She wished they could stay there forever.

But she heard footsteps on the stairs. Frowning, she stood up and brushed the wrinkles out of her clothes. Clint zipped up his vest and went to the bathroom to wash his face.

Steve Rogers, his shining shield on his back, poked his head through their door. "Time to go," he said.

"Go where?" Natasha asked. Had Loki revealed himself? If so, she wanted to be the first one there.

"I'll tell you on the way," he replied. "Can you fly one of those jets?"

"I can," said Clint, drying his hands as he walked into the room.

Steve looked towards her. Can we trust him? his expression asked. Natasha nodded.

"You got a suit?" he asked Clint.

"Yeah."

"Then suit up," Steve said, and left.

Clint buckled on his arm guards. "What kind of army do you think Loki's bringing?"

"I have no idea," Natasha said. "But if you let them kill you, just know that I will never forgive you."

He slung his quiver over his shoulder, and she checked that all of her firearms were in place. "Dinner tonight?" he asked.

"You're on," she replied. They held hands as they walked down the stairs and towards the jet, and if anyone noticed, they didn't say anything.