They had been partners for two years before the first time they fucked.
One reason it took them so long was their busy lives- back to back missions and paperwork and debriefings don't allow for much down time in their profession. Another was that fraternization between agents was highly discouraged in order to avoid compromising situations during missions. But mostly it was because they were both too stubborn to give into their more animal-like urges.
Natalia "Natasha" Alianovna Romonova, for one, took almost a year and a half to get used to working with a partner at all. She had earned the codename 'Black Widow' for a good reason- she worked solely by herself, with no care for a partner or any form of collaboration. It had taken all of her willpower not to tear Barton's throat out and tell SHIELD to go fuck themselves in their first few missions together. But after four or five months, they had managed to slip into a tolerable balance of give and take, working out their own preferences and job styles.
From his own perch on a rooftop nearby, Clint Francis Barton, codename 'Hawkeye', would keep a close watch on the fiery redhead (or blonde, or brunette, or whatever the mission called for. He preferred red.) below, his bow drawn tight in case their target caught on too quickly.
"Your alright down there, Nat?" he would ask her, a little smile tugging at the corner of his lips as he predicted word for word what she would say in response.
"Don't call me Nat," he would hear in reply, knowing that she had to mutter it under her breath to avoid someone hearing and wondering why she was talking to herself.
With Barton keeping a close eye from afar, occasionally joining in as a stranger for the Russian to pass off intel to, and said Russian manipulating and working their client without breaking a sweat, the two quickly climbed the ranks within SHIELD. No one was really surprised, given that Barton had risked his job and life to bring her back to headquarters instead of killer her as his orders had dictated he do. There had been a few times when Fury had tried to assign them to different partners, but the Widow was like a stray cat. The moment she found out she had someone new to work with, she started hissing and swearing in every language she knew. It didn't take long for Fury to change the plans back to Hawkeye and Black Widow, Black Widow and Hawkeye. If they couldn't work together, they worked alone.
It was no surprise when the rumors began to spread that they were knocking boots. Coulson tried to ignore and discourage these whispers, although everyone was sure he thought they were fucking, too. And if Clint and Natasha knew about the rumors, they didn't say anything. Not out loud, at least, and definitely not to each other.
They escaped these rumors on missions, but what became obvious then was the choking lust they had come to fight against on missions. There was an exhilaration that pulsed through them during each firefight they got sucked into. It curled heat into their pit of their abdomens and by the end, they only had their own training as agents to thank for the fact that they hadn't jumped each others' bones yet. If Natasha noticed that Clint's after-battle showers took a couple minutes longer than usual, she didn't comment on it.
"You ready for this, Nat?"
Another mission, another fight. They had been back to back behind a pile of crates in a back alley somewhere in Budapest. Clint's breath had been hot on her ear, and that heat had traveled to her gut fast. She ignored the comment, loading another magazine into her Glock and taking out a couple of drug lords several yards away. It had been easy, mindless. Point and shoot, point, shoot.
A muffled oath next to her had drawn her attention for two seconds, and after taking out another Hungarian, Natasha noticed the shards of what was once a crate sticking out of Clint's shoulder and neck. He was still going, but she knew that those hunks of wood would only work their way into his neck further if left untreated for too long.
"We need cover!" Natasha had yelled into his ear, and the only indication he had heard was that he pressed a switch on his quiver to change the arrow head. The next arrow he released exploded into thick smoke, successfully guarding their movement from their enemies across the way.
Having grabbed Clint's uninjured arm, Natasha had stood quickly and darted back into the alley, down another street, and into a back alley several blocks down. When she was sure that they had long lost their enemies for the time, she had removed a small emergency medical kit and went to work pulling out wood fragments from her partner's neck and shoulder. Aside from the occasional twitch and soft swear, Barton endured the treatment without a word. Even with as quick as Natasha was at patching him up, it still took the better part of an hour for each piece of wood to be carefully removed. She applied a quick layer of disinfectant cream, then laid out some gauze with a sigh, having slumped back against the wall at the end.
Natasha had been vaguely aware of Clint sitting close- too close- with the scent of sweat, blood, and exhilaration still thick in the air. Green eyes had met gray, and then caution disappeared into the wind. His mouth was on hers- all teeth and tongue and hot and wet- then her skirt was up and her legs wrapped around his waist and the bricks were rough against her back and heavy breaths and moans and then it was done.
The realization of what they had done hadn't hit them until they were back at their dingy hotel room. And then, well, they just didn't care at that point.
They had been in the room barely long enough for the door to shut before they were locked at the lips again, clothing being tossed every which way until there was none left. It was a crystal clear memory in each of their brains, full of tangled limbs and hot breaths and a squeaky mattress and echoing moans. It would be impossible for them to remember how many times they rose to completion, but Clint was fairly certain that they had only slept for an hour or two before the faint pink light from the rising sun woke them and sent them on their way to finish what had been started the day before.
After that night somewhere in the slums of Budapest, agents Barton and Romonov had started up a routine of sorts, but only during missions. In their post battle excitement, they would fall together in a twisted mess of their bodies and fuck to the point where neither of them could move, let alone think straight enough.
They kept up a facade while at SHIELD headquarters, for appearance purposes and all that. They would part ways after sparring or their evening meal, but after most of the other agents retired, Natasha would silently appear in Clint's room.
Everyone knew that the rumors had come true, but no one voiced it. Coulson gave the two agents a wide berth in the evening, keeping his disapproving looks to himself. If they ended up in a compromising situation, he thought, then he would chastise them for their careless fraternization. But for now, they were fine. They still carried out missions as flawlessly as was possible, only with more... stress relief involved. Coulson knew them both well enough- they wouldn't risk failing a mission just for a good lay at the end.
This routine lasted for quite sometime. If one or the other was deployed on a solitary mission, then the night of their return would involve absolutely no sleep. It wasn't until after the incidents involving the God of Mischief and the helicarrier that this routine was broken.
Natasha had known that she may have had to kill her partner. He'd been beyond compromised- God only knew what Loki had discovered while he rummaged around in his head. She was prepared to do whatever it was she had to- what was necessary. But what she hadn't been prepared for was that cold look in Clint's eyes when she engaged him. He recognized her, not as a partner, but as an enemy- but Loki had assured her of that much during the interrogation. Loki had underestimated her, though. She had prepared for this. The fight was like they'd rehearsed it. Dip, kick,dive, punch, disable. Fight, dodge, disable. Cognitive reboot.
The hard part had been getting Clint to the medical wing after knocking him out Having fallen through the roof and getting pinned by a rather heavy beam of metal, her ankle could barely hold her own weight, let alone someone else's. But she managed. No one else would take Clint- not then, not after the past couple of days.
"Don't do that to yourself," she had told him, knowing Clint would anyways. He had been compromised- he had compromised them.
But there had been no time to reassure the archer. BY the time Clint had washed the grime and sweat off from their fight, Steve Rogers had come to let them know that they had a lock on Loki, and Clint was more than ready to hunt him down.
It had been a strenuous fight, to say the least. BY the end, hardly any of them could stand (aside from Thor, but he was essentially a God, so he didn't count). They had chocked down their shawarma, if only just to have something in their stomach. Throughout the meal, Natasha's eyes kept darting to Clint, who looked dead on his feet. They were all more than ready to collapse- not necessarily into a bed, but anything that meant they wouldn't have to keep standing.
That night, after Loki had been secured away on the carrier, neither spy nor archer bothered to keep up with pretenses anymore. Natasha had collapsed onto Clint's bed without bothered with so much as a shower to get rid of the crusted blood and sweat that had compiled over the course of the day. Her partner eased himself down next to her, wary of the shoulder she had torqued hitching a ride during the fight.
"Jesus Christ."
"You said it..." Clint muttered, groaning as he laid back and allowed his body to relax into the mattress.
Shifting onto her side, Natasha rested one hand on the other's bare chest, lazily tracing an abstract design onto his skin. "That tops any other mission we've had."
"Even Shanghai?"
Natasha shuddered at remembering the Chinese mission- they had barely managed to break up the sex trafficking ring there, all the while nearly getting lynched by the Triad and narrowly avoiding a couple of pissed off drug lords in the process. "Even Shanghai."
She heard more than saw the wry smile in his chuckle, but then they were silent. Neither had the energy to roll over and take control, as they normally would.
"Y'know... for a while I thought I was actually going to kill you."
Clint's voice barely broke the silence between them, his breath ghosting over her hair. It was what they had both been thinking, but had been too wary to bring it up. Natasha shifted to rest her weight on her elbows, looking her partner dead in the eye. For a moment she thought about her response, then finally she spoke.
"So did I."
Then she leaned forward and pressed her lips to his. It was gentle and slow and nice, nothing like their usual kisses of teeth and tongue and dominance. Clint's hand fell to rest on the nape of her neck as hers slid down his chest gentle, in a caress as opposed to a grope. Their eyes were closed as they focused on nothing more than now- their lips and tongues dancing an intricate, slow tango around each other, their movements delicate and passionate as their hands felt and touched and explored silently, intimately.
It was slow and sweet. They were tired, and exhausted, and passionate- and they felt closed than they had ever felt before, with how their skin melted together and brought them together as one.
After five years of partnership, three years of fucking, and the longest day in the history of SHIELD, Natasha Romanova and Clint Barton made love.