Dr. Christina Fraser was the fellow hired by Eric Foreman to fill in for Thirteen. She was fired immediately after she was introduced to Gregory House, making her most likely the shortest term fellow of all time.
After Robert Chase's disastrous hire of Dr. Kelly Benedict, Foreman was more than happy to accept House's offer to hire Thirteen's temporary replacement. Foreman worked very hard to find Dr. Fraser and in the episode Unplanned Parenthood while House was busy elsewhere contacting the team by phone, Foreman introduced her to House and the rest of the team. House politely welcomed her, then told her she was fired. The team and Dr. Fraser were astounded, but Dr. Fraser slowly left the room as House explained he was once again trying to teach Foreman a lesson about who was in charge and how little actual authority he had. Foreman protested that House could have done that without crushing a fellowship candidate, but House pressed on nevertheless.