Natasha is vaguely suspicious that one of the reasons Clint said yes to his own quarters at Avengers Tower is because he got a good, long look at Tony’s garage. While Bruce and Tony are best friends in the lab (frequently joined by Jane, who has slowly been drawn into the weird little superhero family they’re building), Bruce barely knows which end of a wrench to hold. Clint, on the other hand, has loved classic muscle cars for most of his life, and Tony is more than happy to indulge a fellow addict. Natasha once spent an almost unendurable two days in London stuck in a two bedroom apartment, listening to Clint describe, in all-too-loving detail, a rebuild on a 1972 Satellite, the first car he fell in love with. Clint retells the story to Tony, and it becomes a bonding moment. Go figure. They disagree only in one detail - Clint scorns anything not American-made, which means a whole wing of Italian and German engineering is ruled out, and Tony gets to call him an unsophisticated lout. There's still plenty in the garage for him to play with.
So, when Clint disappears for long stretches of time, she knows where to look.
Some sort of stereotypical testicle-rock is blaring and a pair of Tony’s robots are wheeling around bringing trays of tools to and fro. All that’s visible from her vantage point are a pair of feet in tattered sneakers sticking out from underneath a car she heard Clint describe reverently as a “1970 Plymouth Hemi ‘Cuda,” which means precisely nothing to her but which is apparently Very Important. She walks over and kicks the nearest sneaker, and hears a metallic clank and some muttered cursing.
“I’m busy, ‘Tasha!” Of course, he knows it’s her.
“We’re late for a briefing with Fury. He’s still mad at you for telling Steve that the CIA has Hitler’s brain in a jar at Langley. Standing him up isn’t advisable.”
“I’ve bled all over this goddamn car, which means by rights it’s mine. Tony has to give it to me. It’s man law. My blood runs through it. We are one.”
Natasha kicks his shoe again. “Now, Barton.”
He slides out from under the car and stands up gingerly, stiff from god-knows how many hours of tinkering. His hands are grimy, the kind of worn-in dirt that’s going to take more than a wash to clean off. Pepper got one look at his hands during a communal spaghetti dinner and suddenly all sorts of weird orange-scented mechanic's soap started appearing in any bathroom Clint might possibly use, along with a stash of sturdy paper towels.
The hands are the least of it today. His once-white t-shirt is spattered with car innards. His jeans have grey patches of dust. A smudge of grease smears one cheekbone and his hair is suspiciously...clumpy in spots.
For the normally cat-fastidious Natasha, this should not be a turn-on. By all rights, she should march him to the shower and into something presentable so Fury can take his time yelling at both of them about whatever they’ve done this time. And yet she finds herself clenching a fist in the front of his shirt, leaning forward on her toes to kiss him suddenly and with a great deal of intent. He chuckles against her mouth and falls back against the car, bringing her with him. She drops his shirt and grabs him by the waistband of his jeans, canting her hips forward and into him. His hands have slid down to cup her ass, and with a quick boost, she leaps up into his arms, legs wrapped around his waist.
Clint reaches behind him and fumbles the back door of the car open and they tumble into it. At this point, Natasha learns something new about cars: namely, that a 1970 Plymouth Barracuda has a really tiny back seat. However, she also discovers about twenty minutes later that two sufficiently motivated (and limber) people can overcome such limitations. The two of them are clutching each other, panting, half-naked, and glued together with sweat and dirt, when somebody raps at the window.
“Hi, you two. Having fun?” Tony is clearly delighted. “Hey, circus training really pays off, huh, Barton? And Natasha, wow. I can safely say I’ve never seen you like this before.”
“Shut up, Stark,” grunts Clint, doing his best to locate an article of clothing - any article of clothing - he could drape over Natasha. It all seems to have been flung to distant reaches of the car. Natasha is covering her bare breasts with her hands, and is doing her best to set Stark on fire with her mind.
“So,” continues Tony, “I’ll tell Fury that you guys are a little...indisposed. I’m sure he’ll understand when I explain it. In detail. Ooh, I might have time to put a Powerpoint together.” He saunters off, radiating pleasure, leaving Clint and Natasha to untangle themselves. A great deal of the grease on Clint has transferred itself to Natasha, who now has a rakish black smear over one eyebrow. He can’t help but start to laugh, and a moment later it sets off Natasha as well, the two of them giggling like little kids while they search the car for their clothing.
“That’s it,” Clint wheezes, pulling his jeans back up over his hips. “I’m telling Tony to buy a Dodge Polara. Giant back seat. Acres of room. Space for all sorts of things. Room to stretch out. No loss of blood flow to any appendages.”
“That sounds like you expect this to happen again!”
“Are you kidding?” Clint grabs her chin and leans in for a long, long, toe-curling kiss. “You. Cars. Sex. We figure out a way to add beer and country music, and I’m never leaving this garage again.”
She swats him, seconds away from another gale of helpless laughter. “C’mon, smartass. We’ve got a shower and a scolding to get to. We have to get to Fury before Tony does.”
They fumble their way out of the car and bolt for the showers. Sadly, Clint requires a great deal of scrubbing from Natasha. Fury is forced to wait for them just a little bit longer.