After they're rescued, Steve and Tony start a relationship. Tony says something along the lines of "i can't believe you would still want me now I'm used goods" (referring to his rape), and Steve says "it only made me want you more." He of course is referring to Tony's selflessness, but Tony thinks he means he just wants Tony as a whore and to submit to him, and it sets off a whole chain of misunderstandings.
I remember Steve asks Tony to come to an event with him because he thinks it'll be a fancy date, but Tony thinks Steve wants to parade him as a pet? And Tony calls Steve captain during sex and Steve thinks it's banter but it's really because Tony can't bring himself to calll Steve sir. At the end Tony begs Steve not to tell Pepper and says he'll do anything; Steve is horrified because he thought they were in a loving relationship all along.
I've been searching for this fic for ages- I don't think it's on ao3- so if anyone can direct me to a link I'd really appreciate it!! Thanks so much :)