In the two years since the "Loki incident" as Steve's taken to calling it, he thought he had figured Tony out, understood how Tony thought and viewed the world, how he reacted and what made him defensive. Tony's complex - there's no doubt about that - but Steve thought at least he knew Tony well enough by now to not be overly surprised by the things Tony says and does.
Steve finds out just how wrong he is when he slides to his knees in the shower one morning and Tony says, "We should get married."
It's so unexpected that Steve splutters and pitches forward. "What?" he chokes, staring up at Tony like he's speaking another language, blinking rapidly against the water. "Did you-" Steve has to shake his head. "Did you just ask me to marry you? Now? When I'm about to give you a blow job?"
"What can I say? You look amazing kneeling in front of me." Tony's lips curve into a lazy smirk, the one that Tony knows irritates Steve to no end. "What, not romantic enough for you, Cap?"
"Coming from you, this is as romantic as I'll get," Steve says flatly.
That amuses Tony, Steve can tell, and he doesn't even look remorseful, not that Steve really thought he would. Tony leers down at him and spreads his legs wider, pushing his hips out. "Hopefully soon I will be coming."
Steve groans, rolling his eyes heavenward. This really is the least romantic proposal Tony could ever have done, but in some ways, it's very Tony, and Steve can't fault him for that. So Steve takes the hint and leans forward, kissing along Tony's cock. Tony moans his approval, carding his fingers through Steve's hair.
"You want to marry me, Tony?" Steve asks, flicking his tongue over the head of Tony's dick and holding Tony against the wall so he can't move. "You want the whole world to know that I'm yours, is that it?"
Steve hears Tony's head hit the shower wall.
"Oh, fuck, Steve," Tony says, sounding impatient. "Tell me you want me to make an honest man of you already, and then get your mouth on my cock."
Amused despite himself, Steve takes just the head in his mouth, sucking gently and swirling his tongue around. Tony moans again in relief, but Steve just teases for a few moments before he lets Tony's dick pop out of his mouth. Quickly standing up, Steve pushes Tony firmly against the wall and covers Tony's mouth with his own before he can protest. Steve kisses him deeply, fitting their groins together, and slowly grinds, swallowing Tony's surprised grunt.
Steve rips his lips away abruptly, pleased to see Tony's chest heaving and the slight daze in his eyes. Steve's hands are tight around Tony's hips as Steve keeps him pinned to the wall, still grinding against him. "I'll let you make an honest man of me," he says lowly, "but until then, you'll keep your hands to yourself."
Tony's horrified expression makes Steve grin, and he gives Tony one last kiss before he darts out of the shower while Tony's slack-jawed and frozen, eyes wide.