Tony awoke slowly to the feel of morning sun streaming in his panoramic windows. Everything was quiet, peaceful, the smell of sex lingering in the air from last night and the heat of Steve lying beside him creating an atmosphere he was very familiar with. Ever since he'd invited the other Avengers to stay at Stark Tower this had become a near nightly routine, despite all the teasing he and Steve got in the morning when they both came out of the same bedroom.

He could tell by Steve's breathing that he was awake, but Tony took his time waking up – he'd bottomed last night, Steve owed him. When he did open his eyes, he was greeted with the sight of his boyfriend gazing down at him, propped up on his elbow and smiling.

Tony was sure he'd never get over the way his blue eyes downright sparkled when he was happy.

"You are far too chipper for this hour," Tony joked, rubbing his eyes. Steve laughed.

"It's nearly ten, Tony, it's not that early."

Tony grumbled something, but he was smiling as well. You would be too, if you woke up next to a naked Captain America.

Steve leaned down and pressed his lips to Tony's, kissing him soft and sweet and lazy. Tony sighed quietly; enjoying the moment before they faced the havoc downstairs that was breakfast with a bunch of mutants and assassins.

Steve pulled back all too soon, leaving Tony with a terrible lack of lips against his. He whined indignantly and sat up on his elbows to try and kiss a chuckling Steve again.

But when Tony moved he heard the sound of clinking metal from his chest area, causing him momentary panic because he thought it was coming from his arc reactor, which would be a bad sign.

He looked down and saw the small machine in his chest looking completely fine, glowing dimly, but there was something laying on top of it, something attached to a chain that he could now feel went around his neck.

"Are…are those your dog tags?" Tony asked uncertainly. He looked up to see Steve smiling bashfully, not wearing his signature army souvenir.

"I thought you should have them," he said quietly, fiddling with the metal on the chain and not looking at Tony. "Back before I was frozen, a soldier would give his lady a promise ring to vow that he would come back for her. I didn't think you'd like a ring very much, and…I wanted to give you something that meant a lot to me."

Tony didn't know what to say. On the one hand he would usually poke fun at Steve for being such a cheesy romantic (even if he secretly loved it), but this really was a touching thing he was doing. Steve valued his dog tags almost as much as his shield, because it was one of the few things that still got the same respect as it did seventy years ago, and it served as a reminder of his time in the war. Giving them to Tony meant that Steve trusted him with something that was very precious to him, and honestly Tony was touched by the gesture.

"Now obviously if I ever go into battle again you and the other Avengers will be by my side," Steve rambled on nervously, still not looking at his boyfriend. "But I thought they could be a promise to always…love you, and protect you, and put you before anything else."

Tony Stark was not one to cry in non-life-or-death situations, surely not. The wetness in his eyes and the tightness of his throat were surely due to spring allergies. He made a note to ask JARVIS what the pollen content in the air was today. Maybe he was having an allergic reaction to Natasha – he was pretty sure she was part cat.

He took a deep, somewhat shaky breath and gave his lover a watery smile.

"You like them?" Steve affirmed, finally looking Tony in the eye. He could only nod and throw his arms around Steve, who sputtered in surprise before returning the embrace.

"Damn you and your…romantic thoughts," Tony muttered. Steve chuckled and they gripped each other harder, Tony feeling the dog tags pressing coldly against his flesh. "Now I feel like I have to give you something."

"Don't bother. I owe you for bottoming last night."

When they went downstairs for breakfast Tony kept the dog tags on the outside of his shirt, wanting to show them off. He got a few jibes for them, something about how their lovey-doveyness was the reason Thor preferred to stay in Asgard instead of Stark Tower, but he took no notice. It was his goddamn tower; he could just kick them out if they got too annoying.

After that day Tony took to wearing the tags under his shirt, because they conveniently hung just above his arc reactor so that every time he took a step he could hear them clinking dully. He liked the reminder that they were there, that Steve really did love and prioritize him, because if he was being honest, he felt that Steve deserved better. Steve was this phenomenal, pure, good person and Tony thought that a bitter, selfish bastard like himself was a poor match for Captain America.

He confessed this to Steve late one night, after he had a couple shots in him, and the result was Steve dragging him to the bedroom and fucking him like he never had before.

With each thrust the dog tags clinked against Tony's chest plate, and he thought maybe, just maybe, he and Steve might actually be soul mates.