The fic is basically a "missing scene" from Captain America 2, between the battle on the highway bridge, and Steve, Sam, and Nat being held prisoner in the truck. In it, Rumlow rapes Steve. What I remember that one of the other HYDRA agents was recording it on their phones, but Steve lashed out and managed to destroy the phone. Also, before the horror/pain sunk in, Steve was largely exasperated by Rumlow's assault.
Please and thank you for all your help! :)