One of the things about getting older was realizing all the things that you were never going to do. Climb Mount Everest. Walk on the moon. Fall head over heels in love.
That was just how it was. Tony could see no reason to think anything would ever change in that regard. And he was cool with that.
Until he met Steve Rogers.
It defied explanation. He spent hours hunkered down with JARVIS trying to quantify the variables and force the illogical into tidy equations. All he got for his pains was a cool new version of calculus and a whopping headache.
Pepper was no help. Rhodey just laughed and said it was about time. Natasha's mouth took on a pinched look that said she was trying not to smile.
And then there was Steve. Doing amazing things just by walking past. And every time – every damn time – Tony felt something loose and funny go running around in his chest. He watched Steve go by, stared after him when he had left a room, and counted the minutes until he got to see him again.
"I am so screwed," he moaned, and Bruce just shrugged and said it happened to everyone.
"Not to me it doesn't," Tony said.
"Looks like it did," Bruce observed, and Tony could only slide down in his chair with another theatric groan, because it had, damnit, it had.
Weeks of staring after Steve, of feeling his entire body lighten whenever Steve entered the room, like Steve was surrounded by this aura of something science had yet to discover. Dreaming up ways to spend time with him, taking him on extended tours of the modern world, electricity sparking in the space between them, every nerve alight with potential.
And then out of nowhere, Steve began to look back. And Steve smiled at him, and Tony literally saw fireworks. (He walked straight into a wall, too.)
But it was so worth it.
The thing about Steve's smile was that Tony would never get sick of seeing it. Flying over majestic rivers, laughing over a stupid joke as they sparred together, sitting on the roof and just gazing out at the city. It was all so textbook and pathetic and Tony had never been so damn happy in all his life.
He knew he walked around with a goofy little smile on his face, and he didn't even care. He couldn't remember the last time he had insulted the bots, or made fun of Clint. Rhodey was still laughing at him and Natasha had stopped trying to hide her smiles, and at the end of the day Tony would head off to bed and kiss Steve good-night.
And Steve would smile and Tony's heart would do that funny little jig in his chest, the one that made him swear to himself to never ever do anything to take away those smiles.
"You know, I never expected this," he said, gazing down at Steve lying beneath him, eyes so blue and honest.
Steve just smiled and slid a hand behind his head, fingers carding through his hair, pulling him down for another kiss. "Neither did I, but I'm glad it did."
And Tony could only agree.