baggvinshield:

rumlow was literally only in cacw for the sole purpose of reminding the audience that steve is hopelessly in love with bucky. that’s it that’s the only thing his appearance in the movie accomplished. being a villain, being a terrorist, any rando character could have done that stuff. but the story needed someone who knew about bucky, what hydra did to him, that bucky fought 70 years of brainwashing and programming to remember that he knew the man on the bridge, and would know to use all that to shut steve down at a critical moment. rumlow knows steve and bucky were/are in love, and he used it as ammo against steve.