All but one of the main characters in Scrubs are medical professionals. The show's narrator and main character is John "J.D." Dorian (Zach Braff), a young attending physician, who begins the series as a staff intern. He develops a close friendship with fellow intern and later private practice physician Elliot Reid (Sarah Chalke); their relationship becomes romantic on several occasions, which other characters have noticed. Elliot is driven by a neurotic desire to prove her abilities to her family (in which all of the males are doctors), her peers, and herself. J.D.'s best friend is Dr. Christopher Duncan Turk (Donald Faison), a surgical attending physician. Turk roomed with J.D. at college and medical school, and the two have an extremely close relationship, which is described in season 6 as "Guy Love". During the course of the series Turk marries Carla Espinosa (Judy Reyes), the hospital's head nurse, who acts like a mentor to interns often hiding their mistakes from their attending doctor. Carla is prone to overreaction and compulsively tells her friends how to go about their lives. Two other characters play senior roles in the hospital. Dr. Percival "Perry" Cox (John C. McGinley) is the senior attending physician at Sacred Heart and the hospital's Residency Director. J.D. considers Cox his mentor despite the fact that Dr. Cox routinely criticizes and belittles him. Cox frequently suggests that this harsh treatment is intended as conditioning for the rigors of hospital life. Ken Jenkins plays Dr. Bob Kelso, Sacred Heart's Chief of Medicine. Kelso is cold, heartless and cruel, driven primarily by the hospital's bottom line rather than the well-being of patients. However, it is occasionally suggested that he has a softer side, and that his cruelty is a means of coping with the hard decisions he is often forced to make, stating that when he became Chief of Medicine he thought he'd be "the man". Instead he very quickly realized that the harsh decisions made him unpopular, however, he had to continue his "evil" facade to keep the hospital running smoothly. The only lead character who is not a medical professional is a hospital custodian known only as "Janitor". Played by Neil Flynn, Janitor has appeared in every episode, except for the season two episode "My Lucky Day." An incident in the pilot episode establishes an adversarial relationship between him and J.D., which persists throughout the series. This tends to take the form of the Janitor pulling mean-spirited pranks on J.D., going as far as locking him in a water tank for a full hospital shift.