Tony marks his victims with a black tear and Tony has Jarvis to film him taking advantage of Steve where he subsequently uses it as leverage in their relationship. Also, Tony bars Steve from his room and Steve sleeps in a room where there's no toilet and he ends up relieving himself on the bed or some sort. Tony also implants an inner armour in Steve that only responds to his commands and he capitalizes on it to torture Steve and Steve doesn't know how to admit to Natasha about his situation.
Steve is relieved much later when the Avengers find out about it and it's revealed that Bruce also has a black tear that he's ashamed of.
I hope that somebody will be able to help me! Thanks a million bunches beforehand!