I looking for a story I was reading a while ago, I can't remember all the details but here's what I got: Tony is bonded (soulmate/identifying marks) to most of the team I think, (minus Bucky i think) but he hides his marks from them. Thinking they can't possible want anything to do with him. In the end, some one sees the marks and confronts him I think.
I found one a similar story where Howard burned off the marks, it's not that story. Hopefully someone can help!