I'm looking for this fic I read some time ago.
I think it was a one shot and the Avengers just finished a debrief (at SHIELD?)
Iron Man offered something to the rest of the Avengers and they didn't want to accept. Later Steve told Iron Man that he could change place with him. Turned out that all the others thought that Iron Man had to "pay" Tony all the things he got for the Avengers with sexual favours.
Tony revealed then his identity to Steve - and he was very amused
Can you point me to this story? Thank you!
PS: I tagged with humor, because the fic did not had a dark vibe - even with the misunderstanding (so far as I remember)