Steve really thought Tony would be the possessive one. After all, Tony’s possessive about everything else – his suit, his cars, JARVIS, his time, and even Pepper (though that's all in Tony's head because Pepper never lets him get away with that). So Steve thought Tony would be the one who loved to cover Steve in his mark and scent, loved to keep him in bed until he's wrung every last moment of pleasure from Steve's body, and loved to always put a hand on Steve's hips or arms in a silent declaration of "mine!"
Steve was expecting it, and he was even looking forward to finally having someone claim him as their own even as Steve claimed them in return. Steve felt as if he spent his entire life waiting, in restless anticipation of someone finally coming along and making his heart pound and blood burn, overwhelm his senses. And while Tony does make Steve’s heart pound and blood burn, Steve didn’t realize how much he would end up craving knowing he affected Tony in the same way.
But Steve did.
Steve found himself constantly wanting Tony near so he could reach out an arm and remind himself that Tony was still there. Constantly wanting to keep Tony in bed so Steve could hear more of the beautiful noises that he pulled from Tony's throat as Steve moved inside him. Constantly wanting to see Tony in nothing but Steve's too-big shirts so that Tony would always smell like him.
Unsurprisingly, Tony picked up on Steve's habits and inclinations quickly, much to Steve's eternal embarrassment. But despite Tony's frequent teasing, giving Steve smirks and making not-so-subtle innuendos in front of the other Avengers multiple times a day, Steve got the impression that Tony liked when Steve was possessive. Tony’s never said one way or the other, but he never pulled away or told Steve to stop when Steve couldn’t help himself from putting several bright and large marks on Tony’s neck or absently rubbed his fingertips over the skin just above Tony’s jeans.
In fact, Steve was beginning to suspect that Tony wanted him to be even more possessive, and Steve was increasingly sure of this as the weeks passed because every time he saw the glint in Tony's eyes, Steve took it as a challenge, one that always sparked another burst of possessiveness and often led to Steve dragging Tony back to bed for more hours spent naked and sweaty.
And one day, Steve becomes absolutely sure that Tony craves Steve's displays of possessiveness and encourages them when Thor, who recently discovered the wonders of the Internet, comes barreling into the main living room, holding a brown package.
"Tony!" Thor booms, customary wide grin on his face. "A gift, shield brother."
He presents the package to Tony, looking expectant, and Steve watches, curious about what Thor could have gotten Tony, and also wondering who actually ordered the gift because Thor certainly wouldn't have been able to figure out how to do so on his own.
Tony stands up and takes the package, patting Thor on the shoulder. "Thanks, big guy. That's nice of you," he says, only a touch of sarcasm coloring the words Steve notices.
Thor looks like an overexcited puppy as he eagerly watches Tony open the box, and Steve's curiosity skyrockets when Tony abruptly laughs at whatever he finds inside, which is still hidden from Steve's eyes.
"Where'd you find this?" Tony asks, turning his attention back to Thor, who's practically beaming.
"A truly skilled artisan named Amazon," Thor states proudly, and Tony laughs again, Steve having to stifle his own laughter. "Now you will be able to adorn yourself with your lovers' crest whenever you desire."
Thor's words only deepen Steve's confusion. "What is it?"
Alarm bells start ringing in Steve's ears when Tony slyly glances over at him, one side of his mouth curled up.
"Why, Captain, it's you," Tony drawls, setting the box on the table and pulling out whatever is inside.
Steve's mouth falls open a little when he finally gets a look at Thor's gift. It's a tee-shirt designed to look like the top portion of Steve's Captain America outfit, a perfect rendition with the star and stripes, and Steve can’t speak for a moment, never having expected to see something like that.
Tony holds the shirt in front of his chest, cocking his head and looking down at himself. "This will look fantastic on me, don’t you think, Cap?" he says, and this time, Steve distinctly, though distantly, hears the amused sarcasm.
Thor, of course, is oblivious to the undertones, and merely smacks Tony on the arm in his boisterous way like he always does, still grinning, and then leaves, his retreating footsteps heavy.
Tony turns to fully face Steve, still holding the shirt in front of him. "I bet you'd love to see me in this," Tony says, practically purring the words and giving Steve a faintly leering look, but before Steve can unstick his tongue from the roof of his mouth and respond, Tony leaves too, disappearing down the hall.
Steve blinks a few times, trying to not let Tony's words get to him, but of course his efforts are futile, and Steve groans when he can't help but imagine Tony spread out on their bed in the shirt and nothing else. Feeling a sting of arousal, Steve shoots to his feet and goes in search of Tony, their bedroom his first stop.
"Tony?" he said, opening the door. "Are you in here? What are you-"
The words abruptly cut off when Steve almost chokes on his tongue from the sight in front of him, as if it was plucked right from his mind. Tony's on their bed, naked except for the shirt, bunched up to show his navel, with his legs spread and bent while he slowly strokes his already hardening cock.
Steve would be embarrassed by the needy whimper that escapes before he can hold it back, but there's not enough blood left in his brain for Steve to muster the energy to care.
Steve hardly recognizes his own voice, so deep and rough and desperate, and feels the familiar, insistent throb in his groin.
"So predictable, Captain," Tony says, a slight breathlessness in the words. "And so possessive, getting all worked up seeing me wearing this, wearing proof that I belong to you."
Steve can't deny it. God help him, but he is predictable and he is possessive, and he wants Tony right now, just like this, when he's utterly and completely Steve's, eager to prove it. Steve's moan is loud and unmistakable, and Tony's smirk only widens, his hand moving faster.
"You want to know a secret?" Tony asks. "I like it, I want it, want to be yours and only yours."
Steve's never had much self-control where Tony's concerned, and Tony's heated words are plenty to snap Steve's tenuous restraint, and he moves quick as lightening over to the bed, covering Tony's body with his own and pressing him deeply into the mattress.
Tony moans, arching his back, and Steve wastes no time in getting his mouth on Tony's exposed throat, intent on making a dark bruise bloom there, and letting his hands roam freely over Tony's body.
"I'm going to fuck you while you're wearing this," Steve says, holding Tony's thighs open, rocking against him, "so you know, Tony, so you never forget that you're mine and only mine."
"Oh, fuck," Tony hisses, and Steve feels the muscles in Tony's legs contract, feels Tony shift under him and insistently push his hips up. "Steve…"
"Yes, that's it," Steve encourages. He mouths along Tony's collarbone, feeling the pounding of Tony's heart under his lips. "Tell me who you belong to."
Tony gasps, grabbing at Steve's head and pulling him up until their eyes meet, and Steve sees the familiar challenging glint in them, the one Steve wants to satisfy the rest of his life.
"Make me," Tony taunts. "Captain."
Steve shudders, groaning as Tony's words make something in him feel frenzied and restless, on edge and irrational, ready to pounce. Steve takes in the sight of Tony under him, flushed and aroused, absolutely gorgeous in red, white, and blue, and absolutely, undeniably Steve's.
"Make me," Tony says again, and Steve can't take anymore – he growls, pushing at Tony and pinning him to the bed and looming over him. Only Tony can bring this possessive fever out in him, can make Steve half-delirious with arousal, can cause Steve's heart feel as if it's going to swell until it bursts.
"Mine," Steve almost snarls, and Tony stares up at him unafraid even as his body jerks and his cock presses insistently against Steve's hip, and the glint still in his gaze, provoking and inciting and spurring Steve's lust. Tony never knows when to stop pushing. He just pushes and pushes, and now Steve's going to push back and enjoy every moment of Tony's inevitable capitulation.