It wasn’t like Tony was listening in on purpose.
When Steve had moved into his first apartment, Fury had convinced Tony that some degree of monitoring was essential for security. Normally Tony would have refused that kind of breach of privacy, but then he’d seen the rough and dilapidated area of town that Steve had moved into.
Steve insisted it had been a nice neighborhood in his day, but now he lived on a block surrounded by junkies, gangs, and pimps. Lord knows that Steve could take care of himself, but for all his tactical knowledge he was still remarkably naive about some aspects of the modern world.
So Tony had agreed to Fury’s planned surveillance of Steve’s home on two conditions: first, that it was audio only. Video surveillance was crossing a line, even for them, and audio would pick up any distress from Steve just as well. And second, that Tony himself would be in charge of monitoring the feed, not Fury or anyone in SHIELD. There was no way Tony was letting those slippery bastards get so close to Steve without his knowledge.
Speaking of, Tony hadn’t exactly been forthcoming with Steve about the surveillance. Tony figured Steve was smart enough to know he was being monitored by SHIELD any time he left their facility, and it seemed like the best cover was to maintain a polite fiction between them.
It wasn’t as if Tony listened to live-action audio feeds of Steve at home often. Apart from anything else, surveillance really was incredibly dull, especially when the target was as committed to upstanding behavior as Steve was. Tony had simply coded up a quick filtering program that would alert him if there were ever sounds of distress or battle in Steve’s apartment.
The system had tripped a few false alarms on occasion, usually when Steve was playing his Bing Crosby records on his old gramophone at a higher volume than usual or when he was working out at home, the smash of barbell plates loud enough to trip the filter.
Those times Tony had flipped over to the audio frequency to check that Steve was safe, and imagined Steve’s foot tapping to the strains of Only Forever, or his muscles straining against his pants as he worked out.
Tony smiled just a little as he listened, then after a few seconds flicked the alarm off and let Steve have his privacy back.
So it had honestly come as a complete surprise on the random Tuesday evening that the insistent bleeping had alerted him to a problem in Steve’s apartment once again. Tony had been working late at Stark Industries and had been about to head home, but on hearing the alarm he hurried back to his desk and turned on the audio feed.
There was a lot of white noise at first. Even Tony’s best surveillance bugs weren’t as crystal clear as he would have liked, but he’d opted for discretion over clarity. It took him a couple of seconds to tune out the background hum and hear what he was searching for.
There it was - the sound of heavy breathing, air passing in and out quickly.
It was probably just Steve exercising again. Tony didn’t think his neighbors would be too happy with Steve’s choice to deadlift late at night, but he guessed they were unlikely to raise a complaint.
Then another noise caught his attention. It sounded like a moan, a little involuntary exhale.
Steve was probably just lifting heavier than usual. God knows Tony heard stranger things in the Ultimates’ gym.
Tony’s head whipped around to stare at his screen incredulously. There was no mistaking that sound. It was most certainly not an exercise sound.
Tony’s eyes boggled and he sat down heavily. That was almost definitely the sound of someone having a good time.
It seemed ridiculous to admit, but Tony had never really thought about Steve as having any kind of sex drive. If pressed, he’d have made a crack about Steve only being able to get it up if his partnered hummed the star spangled banner.
But listening in, Steve didn’t seem to need any encouragement, and by the sounds of it he didn’t need a partner either.
The image of Steve sitting at home and jerking off hit Tony like slap to the face and his hand tightened around the arm of his chair.
“Fuck -” Steve cursed, and Tony could only agree.
Tony was about to turn the audio off and let Steve have what remained of his privacy, he really was. He might have been planning to rub a quick shameful one out himself when he got home, but he really wasn’t intending to snoop.
But then he caught a sound. Not the rhythmic slap slap slap he would have expected from a hand wrapped tight around a dick moving in tight, controlled bursts.
No, this sound was wetter, slicker, squelchier.
That sound, Tony’s many years of ample experience told him, was almost certainly the sound of thick, lubed fingers sliding in and out of someone’s asshole.
The arms of his office chair creaked ominously as Tony white knuckled them. He was hit by a vivid mental image of Steve on his knees, bending himself over his own sofa, slick fingers shoved deep inside his ass.
Tony swallowed thickly.
And then, suddenly enough that Tony scrambled to his feet, afraid he’d somehow been caught out, the sounds stopped.
Tony strained his ears, desperate to pick up any clue as to what was happening. There was some kind of scraping plastic sound and then there were wet sucking noises that went straight to Tony’s dick.
He was pretty sure that whatever Steve was doing now, it involved something going in his mouth. There was a muffled mphf that sounded satisfied and, somehow, smug.
Tony braced himself over his desk and looked down to notice that he was blatantly hard, his dick tenting his slacks.
Listening to Steve go about his day without his knowledge was not cool, Tony knew. Listening in on him jacking off was definitely invasive, a further line crossed. But he’d been telling himself that this was just a jape, a bit of fun, the sort of thing that friends might tease each other about. The fact he was clearly getting off on listening in did rather put paid to his excuses.
Tony slumped back into his chair, feeling guilty and slimy, but not enough to turn the surveillance feed off. He wished he had a drink.
Steve was quiet once again, but if Tony strained he could pick out the sound of a determined hum like Steve would give before he went into battle.
Tony could picture it so clearly: Steve, on his couch, staring down at an oversized dildo, a look of steely determination on his face. Steve fisting his cock in big, greedy swipes, the head peeking out between his big hands as he went. Steve bending over, pouring lube all over his hand and his ass before sliding fingers into himself, his eyes widening with shock and his mouth slack with pleasure.
Tony’s hand ground down against his cock involuntarily, the pressure shading into pleasure and guilt as he indulged himself.
He couldn’t stop listening though, hanging on every noise from the speakers, every suggestion of what Steve could be up to. He heard shuffling, like Steve was rearranging himself, getting comfortable and prepared, like he was planning a tactical operation. Wet, slick sounds that must have been more lube, spread over something plastic and harder than a human body.
Then a deep breath, Steve steeling himself, and Tony knew the exact look he’d have in his eye as he sized up a challenge. Tony could barely breathe, every muscle in his body coiled up tense as he waited for the next act of the drama.
A tiny gasp, something unfamiliar pushing against Steve, slight slickness that Tony could imagine Steve spreading around his hole. And then another heavy breath, a moment of silence, and then a long, slow slide and an incoherent moan that echoed out like it had been ripped from Steve.
Tony hadn’t realized that Steve was capable of making such a noise, let alone that this was how he chose to entertain himself on lonely nights. Tony had a feeling he was not going to be able to forget that sound any time soon.
Giving up any pretense of being a decent person, Tony popped the button on his pants and shoved a hand into his underwear. He was already hard and wanting, just getting his fingers around the tip of his cock made his head swim.
There was a grunt, more shuffling and another slick noise, then the sound of skin slapping against skin, the rhythm hard and sure. God, Steve was really into this. Had Steve been planning this all day? Thinking about how he’d get home from a busy day of Ultimates business and reward himself with a ride on what must be a favorite toy? The pace was fast and sure; Steve certainly seemed like a man who knew what he wanted.
Tony was still teasing himself, gently running fingers along the head of his dick like he could pretend that this didn’t really count as jerking off over a teammate without their knowledge.
His hand slipped into the same rhythm that he could hear Steve setting, the same hard pace. He closed his eyes, leaned back, let himself consider what he might do if Steve were here with him, if he were the one wringing those noises out of Steve.
“Yes… yes… yes…” he heard Steve chanting, rough and throaty and like he wasn’t even aware he was speaking.
Tony looked down at his hand shoved into his pants and figured he wasn’t fooling anyone. In for a penny, in for a pound, he decided, and pushed his pants down to his thighs, freeing his cock and wrapping a hand all the way around it with a gratified moan.
The noises Steve was making were becoming even more obscene, a sort of wet gasping like he had his face planted into a cushion and was overwhelmed with the pleasure. Tony pictured him overcome, overworked, drooling into the sheets while he was taken.
Would Steve actually let Tony fuck him? Until a few minutes ago Tony would have said that anyone trying to put anything up Steve’s ass would be likely to lose a limb, but judging by his recreational habits perhaps he wasn’t as averse to the idea as Tony had assumed.
“Fuck, fuck, fuck, fuck,” Steve was gasping, and Tony would have been genuinely scandalized to hear Steve cursing like that if he wasn’t so out of his mind with want right now. Instead he pumped his cock harder, slamming his hand back in firm strokes in time to Steve’s gasps.
Another break in the rhythm that made Tony want to scream with frustration, then more shuffling, then a rasping, throaty “Goddammit, yes,” as Steve readjusted himself. He must be taking his toy so deep, pushing it so far inside himself, and Tony could imagine how good it felt, how much Steve was loving it.
Tony thought about the look on Steve’s face, the astonishment melting into warm pleasure as he brought himself off, and that was really doing it for Tony, the thought of Steve’s face as he gave himself over to orgasm was enough to have Tony right on the edge -
Tony’s eyes flew open and his hand jerked away from his cock like he’d been shocked. Because that had almost definitely been Steve speaking his name, and that must mean that Steve had… had found the surveillance bugs? Or that he was calling the Ultimates help? Or that -
That was surely the sound of Steve, sated and happy, rolling down from a delightful orgasm.
An orgasm he’d had while thinking about Tony?
Tony’s mind whirled. He sat stock still, eyes wide and cock still hard and bobbing against the edge of his desk.
Something needed to be done.
He was on his feet and shoving his cock back into his pants before he could think better of it, feet carrying him down to his armory on instinct. A tech entered the room as he was pulling on the armor vambraces and Tony waved him over, instructing him to help attack the chestplate.
“Is there an emergency, Mr. Stark?” the tech asked, looking concerned.
Was there ever. But Tony figured “Captain America just said my name while jerking off and I have to get to his apartment right now,” was not something this particular underling needed to hear. He waved a hand instead and made an excuse about late night flight tests.
The minutes that it took to get the armor prepared felt like hours, but finally he was ready and he shot into the sky over New York. He honed in on Steve’s home and kicked his repulsor boots up to maximum, speeding towards the shitty apartment block at reckless speed.
Landing on the sidewalk with a thud, he pushed his way into Steve’s block and clattered up the stairs, shedding pieces of armor as he went.
“Steve!” he yelled, knocking loudly on the worn apartment door. “STEVE! Are you there?”
The urgent throb of want settled low in his belly and he fervently prayed that Steve was still in and still in the mood. He hadn’t gone out, surely? But there was only deafening silence from the other side of the door.
He banged on the door again. “STEV--”
And then the door was opening a fraction, slowly revealing a ruffled and extremely grumpy looking Steve. “Can you shut the fuck up?” he said sourly. “It’s two in the morning.”
Tony glanced down and smugly noted that Steve was mostly naked. And damn, it was a good look on him, even if Tony could only admire it through the crack of the door.
“Did I wake you up?” he asked with a shit-eating grin.
Steve’s face hardened and he looked like he was about to say something acerbic, so Tony decided not to give him the chance. He casually pushed the door open and slipped inside the apartment without waiting for an invitation.
The air smelled like sex. “Were you having a party?”
Steve’s brow furrowed like he was going to argue before settling into his usual grim-to-neutral expression. “No,” he said flatly.
“Because Fury was worried,” Tony said. Just a small lie in the scheme of things.
“Fury?” Steve asked, though Tony could already see the wheels in his head turning.
“Oh, don’t be stupid. You must know he has agents listening in,” he replied cheerfully. Not exactly the truth, but near enough.
A look of stricken shame crossed Steve’s face and he shoved an arm out to block Tony’s way. Now Tony was sure he was onto something fun. He glanced around Steve’s body and took in the messy couch splattered with what was almost certainly cum and next to it, lying on the floor, an amply sized bright red dildo. Steve was clearly a man of considerable enthusiasm.
“Looks like my sort of party,” Tony said with a lascivious smile.
He enjoyed the sight of Steve squirming for a second before he managed to pull himself together and tilted his chin a fraction. “What I do with my own time is none of your business, Stark.” Steve was clearly aiming for unrepentant but Tony could see the worry lines pinched around his eyes.
Much as Tony enjoyed teasing Steve, he really didn’t want him to feel ashamed over a dildo, of all things.
He let his face relax into a genuine smile. “Oh, don’t mind me. I’m the last person who's going to argue with you about what you should be doing in your own time. Not when it looks like so much fun.”
Steve looked somewhat mollified but still skittish. This had to be played carefully. “But if you ever wanted to invite a friend…” Tony offered, trying his best to be gentle, “... I’d RSVP in advance.”
Every line of Steve’s body was taught and tense, and there was a moment when Tony was almost positive that he was going to punch him. But then Steve softened, deflated, let out all that tension. “Ok,” he said, quietly.
Tony froze for a moment. Despite his bravado, he hadn’t really thought Steve would say yes. God, maybe if this went well, Steve might even agree to go on a date with him some time. That was more than he had dared to imagine possible.
Then he met Steve's eye and a rush of fondness washed over him. He could do this. They could do this.
Bouncing on the balls of his feet, Tony leaned in until Steve was very close indeed.
“Ok,” Steve said again, the faint hint of a smile ghosting around his lips.
Tony didn’t need to be told a third time.