Tony knows exactly what to do when he's trying and failing to sleep: his fingers are twitching, eager to be doing something, and Steve's not in bed, so it's an easy switch to go from staring at the ceiling to pulling on pants and nothing else and heading for the gym.
Steve's still at it, still trying to put a hole in his punching bag when Tony finds him, and for a moment Tony just watches him, admires the form and the coiled power Steve's got in his arms.
He'd ask what was wrong, but he knows; he was there during the argument, and he's not budging from his position.
But he loves Steve, and he knows how he works, so he knows how to help. (Even when he's the cause of the problem.)
Which is to say, he almost gets a free punch in, almost gets the drop on Steve, but Steve's good, better than good, and for a few frantic minutes Tony's taking blows meant for the punching bag and he's going to bruise, and it's only the repeated sparring lessons with Steve that let it go for a few minutes.
Steve's still angry, still frustrated enough not to pull his punches even when he recognizes who it is, and finally Steve pins them down on the mat, holding Tony's wrists over his head with one hand, gripping his throat with the other.
"Feeling better?" Tony asks, flashing Steve a grin.
"No," Steve says, but he lets go of Tony's neck. "Self-sacrificing idiot."
"Love you too," Tony says, tipping his head back when Steve goes to lick and bite at his neck, moaning.
There's a quick mental debate on how best to encourage him, then Tony tugs at his wrists again, listens to how Steve's breathing increases, mouth stilling over Tony's pulse, and yes, good.
Steve rolls him over easily, even without Tony's help, and then Tony's got his cheek pressed into a mat as Steve holds his wrists with one hand behind his back and forces his pants down and off with the other.
"Steve - " Tony starts, intending to say something relevant, but he breaks off into nonsense as Steve pushes a finger into him. There's no lube and it's going to burn when Steve fucks him into the mat and Steve's going to apologize and be gentle later, but Tony knows Steve. Steve needs this, he'll watch Tony wince when he sits and his smile will be satisfied and all the genuine guilt he can summon up at the drop of a hat won't erase that Steve needs - likes - to utterly destroy Tony at times. Needs to let go and stop worrying whether Tony can take it or not.
Which is a really stupid reason for Tony to be reckless in combat, but face it: Tony's going to be reckless no matter what he's doing, so if there's a side benefit of making Steve angry at him, so he can let loose -
Tony shouts, body tensing as Steve slams home.
He tries to claw at the mat, biting back frustrated whimpers as Steve keeps his wrists behind his back, tries to move back against Steve and Steve's rock-solid grip on his hip stops that, doesn't let him do anything other than groan and take it.
"S - ah - fuck - "
Steve doesn't stop, doesn't let up, and he's silent which means he's really angry this time, which means that it's good that Tony came down here, good that he's letting Steve do this to him.
He comes with a wail, squirms because he hadn't meant to, because he'd been overwhelmed, and he pants into the mat, moans into it when Steve comes in him, hot and wet, and then Steve's pulling out of him, turning him over, kissing him hard, and everything's going to be sore later.
"Feeling better?" Tony asks minutes later, tucked against Steve's chest, an arm curled around him protectively. They're still on the mats, but they won't sleep there, Tony knows that Steve will get them to bed sooner rather than later.
"Tony," Steve says quietly, then he exhales, a huff of warm air into Tony's hair. "Yes."
"I'm glad," Tony says, and he tilts his head up to kiss Steve.
He's sore, he'll have bruises, but it's true: he's glad.