#1 The way his nose crinkles when he laughs
One of the first things Steve noticed about Tony was the crow’s feet around his eyes, the kind that only appear when someone laughs or smiles regularly. He liked them then, even with everything else going on and Loki’s staff messing with their minds and the whole world going to Hell in a handbasket. His eyes squint when he smiles widely and even when he has his shades on, the crow’s feet reveal that Tony Stark knows how to smile widely.
It doesn’t take Steve long to realize that the wide smile Tony wears is for the public. It crinkles his eyes, yes, but it’s all for the show, it’s not his true smile. His true smile emerges when he’s truly enjoying himself, when he’s laughing at his bots, or with Rhodes and his nose does this thing where it scrunches and…Steve can’t quite explain it. Something about Tony’s nose and his laughter make him all warm inside.
He later learns that feeling means he doesn’t have to be on his own anymore.
#2 His fingers
Tony’s hands are a thing of beauty. They create delicate things, they hammer steel, they operate weapons of mass destruction, they soothe DUM-E when his programming needs updating and the bot is letting out small beeps of distress. But Steve likes them the most when Tony is relaxed and playing the grand piano, lost in his thoughts. His fingers splay along the keyboard as he cocks his head and reaches back to the melodies his mother taught him when he was a kid. They trace out songs of times when Tony hadn’t been through that much pain and betrayal, when he still had his mother to love and cuddle close to.
Steve has never learned to play. Back when he was a kid, it was about money and access—paper and pens were way easier to came by, and drawing became his way of escaping his daily life. Later, there was no time to learn to play anything but his shield, and then he was busy trying to survive aliens and the fact that he’d been iced for 70 years.
And now?
Well, Steve’s fingers still are more adept at capturing fleeting moments on paper. Back then, he used to retreat to a secluded corner to steal a moment for himself but now he likes to draw in Tony’s workshop or in the music room. The controlled chaos in the workshop or the slow, thoughtful notes that dance in the air and anchor him to this time. To this place. To here and now, with these people.
He’s been drawing Tony’s fingers a lot lately.
#3 The dip in the small of his back
He’s not sure why he’s surprised to learn Tony used to do ballet. It’s obvious, now that he thinks of it: his poised posture, the way he walks like he’s always ready to pounce, the way his chest expands (as much as it can), and his back arches when he gets ready to eviscerate some idiot with carefully aimed words and his blinding mind. Maybe it’s the way Steve still associates ballet with ethereal, delicate ballerinas in tutus that look like clouds when it’s raw power, diligent work, and dedication all packed into meticulous core control. You can’t perform on the stage purely on your looks.
It’s the same with Tony.
He often wears old, slightly baggy jeans and ratty t-shirts at home which is perhaps the reason that Steve nearly walks into a wall when Tony stalks in after a board meeting in his shirtsleeves, his suit jacket discarded somewhere.
It’s the first time Steve decides on a tactical retreat purely on the basis of sheer want that hits him when his eyes track the way Tony’s tailored pants hug his legs and his behind and how the close-fitted vest accents the dip in his back. Steve wants to grip Tony’s waist and test just how well his fingers fit into that dip. He wants to splay his hand on the small of Tony’s back and steer him closer and if other people see them, well…at least they’d know whom Tony belongs to. He wants to—
Fuck.
(Well, that, too.)
#4 Snoring
Steve doesn’t like quiet. Most people have this strange misconception that just because he’s from the past, the current noise and activity of a big city is too much for him. They forget that he grew up in a home with cardboard walls that let all sounds through and then he went into the war where silence meant either that something was about to happen or something had happened and everyone was dead.
Silence was his constant companion when he was in the ice.
He doesn’t like silence.
Falling asleep in Tony’s workshop comes as a surprise for everyone else but Steve (and Natasha but he’s pretty sure she’s impossible to surprise). They don’t realize how soothing it is for Steve to have a constant reminder around him, to fall asleep to a steady reminder that he isn’t alone, this isn’t a dream, he’s not been left behind again. On the third time he nods off in the workshop sofa, Steve wakes up under a pale grey, soft, and warm blanket and when he asks Tony about it, he shrugs and mumbles something about finding an old thing in the cabinet, don’t worry about it. (Steve looks it up online later and finds out it’s an organic cashmere-silk blend throw blanket with way too many zeroes on the price tag. He very calmly closes the tab and doesn’t call Tony out on it.)
The first time he sleeps in Tony’s bed, he doesn’t even realize the silence because of the noise inside his head. Was this a one-time thing? Will he get to have this again? Is he allowed to touch now, to kiss, to hold? He falls asleep and wakes up to the blaring of the Avengers alarm and then he has too much in his mind to think about silence.
And then it keeps happening. He falls asleep tangled up with Tony, the quiet whir of the arc reactor, the way he isn’t still even when he’s sleeping. He twitches, mumbles, moves, and snores. Sometimes, Tony starts crying or screaming in his sleep and then Steve is there, holding him close and stroking his hair and back until the shaking subsides and his wildly beating heart calms down. And sometimes, Steve wakes up with a silent gasp, cold and desperate for a sign that he isn’t in the ice anymore, and the steady snoring next to him is a safe sound to latch on to and climb back from the depths of his own mind.
For someone else, it would most likely be annoying but to Steve, it’s a relief. He wakes up to the familiarity of Tony’s body and all the ways it reminds Steve that he’s home.
#5 His eyes
They say eyes are the mirror of your soul and boy, does Steve agree. Not for himself, though, he doesn’t think his eyes are anything special but Tony’s eyes are something else. They can be anything from warm brown to amber to almost black and as cliche-y it sounds, Steve would gladly drown in them.
He used to wonder why Tony wore shades everywhere but he doesn’t wonder anymore. Tony’s eyes reveal everything and nothing and if one isn’t blinded by his charisma or worked to near-senseless rage by his antics, one can read his eyes like an open book.
Was it always this easy?
Steve isn’t sure.
But in the morning, after he’s woken up and gone on a run and then taken a shower, he likes to return to Tony’s side to just look at him and wait for him to wake up. (”Not creepy at all,” Clint commented once and then let out a yelp when Natasha pinched his ear and told him to shush or she’d tell everyone about that one time in Prague. Clint shushed.)
That moment when Tony’s breathing changes slightly and he scrunches his nose and lets out a small sound like a disgruntled cat and then his eyes flutter open? That. That’s why Steve waits for him to wake up. Because for a moment, Tony’s eyes are sleep-hazy and unfocused as he takes in his surroundings. Knowing how Tony used to wake up after Afganistan and the Chitauri invasion, going from nightmares to hyper-focused in a split second, this languid, lazy swimming back to consciousness in Steve’s presence never manages to make him humble. That Tony feels so safe next to him that he can luxuriate in the syrupy in-between state of sleep and wakefulness. That he trusts Steve so close to him.
And then Tony blinks and his eyes focus on Steve and they go from sleepy to openly affectionate and all Steve can do is bask in it.
He can see Tony’s eyes and in them, he sees himself.
(If they often don’t quite make it to the kitchen for lunch, well, that’s their own business.)