It's two in the morning, and Steve is thrashing the bag.
For all the benefits the Serum affords him, the one he hates the most is that his stamina is unbeatable, even to himself. It happens only rarely, but some nights he'd just like to get off and go to sleep, and all his prior attempts to do exactly that have ended in disappointment and chafing. He doesn't have to be a cutting-edge thinker to know that sexual frustration is... well, frustrating. Before the Serum, it was never a problem; now he has urges with no desire, and he'd more accurately describe it as a side effect.
He outlasts himself, not just physically, but mentally; sooner or later he realizes it's been ten, fifteen, twenty minutes, lying in bed and stroking himself into this God-awful boredom. It's pathetic, especially in the oversexed city he's found himself in. The billboards on the street are more risque than the pin-ups he used to like, and even they never really gave him the jolt that they seemed to give other guys. They were only pictures, paper dolls; pretty in their way, but no more erotic in his eyes than postage stamps. They'd laughed at him then, assuming that he was just the faithful type, and that he only had eyes for Peggy or Bucky. He figured they were right.
The one time he found himself desperate enough to actually brave the frightening online corridors of modern sex entertainment, Steve found himself more than a little disgusted with the hollowness of it, the obvious, manufactured dullness; no different from the pin-up girls, just animated and done up in brighter colors and less natural proportions. He took an evening to himself, scanned the internet for something he might like, found most of it revolting, and then never bothered with it again. He thinks it's starting to suggest he's somehow dysfunctional, that the Serum has desensitized him somehow; the thought makes him glad he's never had the chance to disappoint someone in bed with it.
And really, that's what makes it all so difficult, on nights like these; it's hard enough to let go of his time and the world he knows, and it feels so petty that this is the part of his humanity the Serum took from him. He'd love to not need anything more complex than a pin-up girl and a few minutes alone to get a little bit of relief, but in the same way that he sometimes breaks dishes and bones without trying, the simple things just aren't enough for him. It makes him think of Bruce and hate himself, because really, compared to him, what does any man know about losing himself?
So it's two in the morning, and Steve is thrashing the bag. It's not easy to exhaust himself; he can run marathons without tiring, he can fight for hours. The bags that Tony designed for him don't break down or burst open like the normal ones, they're heavier and filled with tougher stuff than sand, but they still can't take his full strength for very long. It's a problem Tony and Bruce have been working on on-and-off for weeks.
He lets his fists fly in a flurry of jabs, experiments with knee strikes; a right cross swings the bag back and forth, so he mimes a sidestep just to burn a little more energy, counters with an elbow strike, keeps coming at it until the thing pops off of its moorings and slides across the floor, ending in a heap a few feet away.
Steve curls his lip at it in distaste; hadn't even worked up a sweat yet.
He sighs, and goes to scoop it back up; the hooks have broken again. Tony had fitted it with a magnet to keep exactly this from happening, but that piece seems to have broken off at the base, which means it'll need whatever piece of needlessly overcomplicated StarkTech craziness was holding it together repaired or replaced. It'll have to go down to the lab.
So he throws it over his shoulder and hauls it downstairs; Tony and Bruce rarely get to sleep before three, especially not when they have a project, and they always have a project. They should still be down there.
And they are.
It's a sight he'll be seeing when he closes his eyes for a long while: Bruce, facing away from him, his shirt open and pooling on his elbows. He's just barely sitting on the edge of the worktable and slowly rocking his hips back and forth, guided by a hand pressed against the small of his back. His slacks hang loose on his hips, suggesting they're open, and it's not until he catches the faint outline of blue light on Bruce's thigh that Tony is kneeling in front of him.
When Tony stands up, Steve can see the wetness of his lips, the soft edge of his smile as he presses close against him, and murmurs softly into the graying hair at Bruce's temple. "Too much?"
Bruce shakes his head minutely, dropping forward against Tony's shoulder. A fine tremor runs through him as their bodies touch; Steve notices that his hands, locked in a kind of loose parade rest behind his back, are wrapped around the ends of a short steel bar. "N-no-- but--"
"I see." The hand on Bruce's lower back urges him foward again, this time in a grind against Tony's body that makes him gasp and shudder. "Easy; relax. You're okay."
Steve stands there like an idiot on the stairs, watching the two of them when he knows he really, really shouldn't be seeing this. He should leave, he should pretend he never saw any of it, but as strange as it is-- why the bar? Why is Tony controlling Bruce's movements?-- there's something so intense and so intimate about it that he can't look away, even if what Steve can see with his own eyes is strictly R-rated.
They move like they're locked in a slow dance, a steady rhythm that matches the pounding of the pulse in Steve's ears far, far too well for his own comfort, and when they stop, Tony rests his hand over Bruce's heart and pushes him down onto the table. His hands are pinned under him, forcing his chest up and out, and Steve is gifted with a full view of his hard, flushed cock resting wet against his stomach.
Tony runs his fingers over the soft expanse of Bruce's chest hair, edged in blue from the glow of the Arc Reactor. "I like this," he muses; there's a softness to his voice that Steve has never heard before, and the heat in the pit of his stomach flares with it. "My lights look good on you, Bruce."
The good doctor's response is a helpless, formless whimper, followed by a sharp gasp as Tony bends down to kiss his throat, the faint hint of teeth in each brush of his lips. When he lifts up again, he hooks his fingers in Bruce's elbows and hauls him up, turns him, and pushes him back facedown against the table.
It's sudden, swift and deliberate-- why doesn't he move like that in combat?-- and Tony spends a few long moments firmly adjusting Bruce's body to the proper angles: hips slighty canted upwards, shoulders pinned, legs parted, hands occupied. When he seems to be happy with Bruce's position, Tony seals the whole of his body over his back, and thrusts slowly against him-- into him-- to a soft litany of Bruce's unhindered gasps and moans.
And here, it clicks in Steve's mind why he can't look away, and it's exactly why he shouldn't be watching this in the first place. He takes great care not to make too much noise as he heads back upstairs with the punching bag over his shoulder, and retreats to his own bedroom, red in the face and just a little short of breath.
He comes hard into his own hand with only a few strokes, eyes closed, going over the little details of the scene with an artist's recall for the image: Tony's gripping hands and focused eyes, the heaving of Bruce's chest and his white knuckles, their clothes half-undone as if they couldn't have waited even if they'd wanted to. It was intimate and real, their pleasure palpable, the trust between them tangible-- and they were Bruce and Tony, his housemates, his teammates, and his friends; the furthest possible thing from paper dolls.
It takes a while for him to come down from it, but exhaustion follows closely on the heels of relief, and he lazily cleans himself up before he decides to feel guilty about it after he's had a night's sleep. At the very least, it can wait until the scent of their sweat fades from his memory.
Steve comes down for breakfast the next morning and he feels like he woke up on the moon. He meets Tony and Bruce for steak and eggs as usual, and tries very hard not to act as if he'd had his first successful orgasm in over seventy years to the sight of the two of them making love.
It almost works. Tony gives him a thorough once over, and offers him a look of mild, pleasant surprise over his suspiciously-large helping of breakfast. "What side of whose bed did you wake up on, Steve?"
"Is she nice? Anybody we know?" He's got nerves about him, like he's trying too hard to find this very amusing.
"Wha-- no, no. I just slept well, that's all." Steve pours himself a cup of coffee, pointedly putting his back to the table to obscure the redness in his face.
"My God, you flash-fry when you're embarrassed. JARVIS, what shade of pink is that?"
"Tony, give it a rest. JARVIS, don't encourage him." Steve frowns over his shoulder at the swarthy jerk, and seriously wonders if this Tony is the same one from last night. "I have trouble sleeping since they thawed me; this was the first good night's rest I've had in awhile." It's the God's honest truth and he's sticking with it.
"...Okay, now I know something's up." Tony leans his chin in his hand. "You don't even want to fight over it."
"I never want to fight with you, you just won't have it any other way." Steve scowls and comes to sit down, and tries very hard not to notice that Bruce is watching the way he walks.
"Fine, fine. Bruce?"
Bruce looks up, and has on that sweet, deceptively harmless, I'm-not-taking-sides-because-you-guys-are-too-funny smile. "Hm?"
Tony pours the remaining eggs and bacon from his own plate onto Bruce's before he goes to put it in the sink; it leaves the doctor's own plate piled high again. "Polish those off for me, would you? I'm getting an early start. Since somebody is being frigid and not giving me my morning argument, I need to find something else to warm my brain up."
There's something about the way Tony says it-- "for me"-- that sounds like it's more than just asking Bruce not to waste food he doesn't want himself. It's subtle, but for just a second, there's a shadow of the lover Steve saw in the lab last night, still looking out through Tony's eyes. He's so caught up in it, pondering its meaning, that he misses Tony's actual departure downstairs.
He also notices that Bruce does indeed clean his plate.