The First Day

The Winter Soldier is starting to make stupid mistakes in the field, which is Bucky's way of trying to wrest back control and sabotage his handlers. Hydra brings a new doctor to figure out what's wrong with him and fix it. As she spends time with him, she becomes fond of the Winter Soldier, and he becomes fond of her. Bucky has other ideas.

Or, a fic in which the Winter Soldier is the good guy and Bucky is actually the bad guy.