Aromantic Tony Stark guys
When Tony’s a kid he knows he’s not supposed to be much interested in romance, but here’s the thing about being a child genius. Most people forget you aren’t actually an adult because you fake being one so well, so people ask all the time who he has a crush on. The answer is no one, he has gadgets to build and that is far more interesting than the romance movies he’s been forced to watch with friends. But people don’t think that’s an acceptable answer and it’s Obi who finally thinks to ask something different. Instead of the dreaded “who do you have a crush on?” its “well there must be someone you think is smart and cute.” Which, okay, duh. There’s this girl in his class and she makes the best comments when people underestimate her ability to build things and he can relate because people underestimate him too, hazards of being a kid in college.
When Tony’s doing his Master’s degree everyone is going to insane lengths to find a life partner but he doesn’t really care. Not because he doesn’t want someone to spend the rest of his life with, but because he’s never bought into that “go to school, get married, have kids, live out your American Dream” bullshit that gets pushed onto people all the time. When someone asks who he wants to spend the rest of his life with he says Rhodey because he couldn’t think of anything better than living the rest of his life out with his friends. People laugh, and someone calls him immature because you can’t live with your friends, Tony, you can’t live out your college days forever. Except that wasn’t what he was trying to do, he just didn’t want to get married and have kids, Rhodey was there for the company, not because he wanted to spend the rest of his life partying (though he wouldn’t mind that either). Rhodey notices how crestfallen he looks but Tony dodges the subject and Rhodey never brings it up again.
By the time Tony is an adult he has a pretty bad reputation for being a womanizer, but he doesn’t understand it. All the women (and men, but people don’t talk about that) he’s slept with were all consenting adults, and he made sure to tell them point blank he wasn’t looking for romance. They all knew what they were walking into before they got there, and they all sighed NDA’s after too, for good measure. But people hated him for only ever having sex with women (but never the men), and everyone he slept with was cast as a victim in Tony Stark’s Womanizing Way’s and he just didn’t see the problem. Why was he a bad person for only wanting sex? Why would it have been less demeaning if he was dating the women (or men)? They all made informed choices and for the life of him he had no idea why everyone hated him so much for not “settling down” with someone, he just didn’t have an interest and he was getting really fucking sick of people asking.
He doesn’t think about romance for a long time, he has no time between Afghanistan, Obadiah, dying, the Avengers, everything else. It isn’t until Steve starts asking questions about all those damn letters in the LGBT+ acronym that he stumbles across the solution to his lifelong problem.
The Avengers put him in charge of research, probably because they all think it’s hilarious when Steve gets an accidental sex talk from Tony but he thinks making Steve blush is hilarious too so he’s fine with looking things up. He makes sure to read a little on each letter so he at least has some idea of what he’s talking about but it still takes awhile to find “aromantic”. When he looks over the term’s definition- not experiencing romantic attraction- he’s immediately interested because he knows exactly what that’s like.
He reads for hours before Natasha and Steve finally hunt him down in the lab, finding him surrounded by articles, blogs, and various websites because things finally made sense. He wasn’t a horrible womanizer (okay, so he was a pretty crappy person then, but not because he only wanted sex), he was aromantic. He hadn’t had crushes or whatever because he was aromantic, he hadn’t wanted to “settle down” not because he was emotionally stunted or immature, he was aromantic.
And suddenly things were put into prospective for him, plus he got the pleasure of watching Steve blush when he explained in excruciating detail how he had come to the conclusion that platonic relationships and sexual relationships had been all he was ever interested in.