In Sacred Heart

Cox constantly berates the residents, giving John "J.D." Dorian female nicknames (e.g. "Tiffany", "Jennifer", "Carol", "Betsy", "Lindsey") and regularly calling him "Newbie". He also calls Elliot Reid (Sarah Chalke) "Barbie", Turk (Donald Faison) "Gandhi" and Bob Kelso (Ken Jenkins) "Bob-O", "Bobcat", "Bobmeister", "Big Bob", and "Beelzebob". The one person he openly admits to tolerating is head nurse Carla Espinosa (Judy Reyes). Throughout Season 1, he and Turk compete for her affections, with Cox eventually bowing out when he sees that Turk and Carla are in love. In one episode, it is seen that Cox helped Turk with how to deal with women when they are mad, Turk eventually taking Perry's advice. Turk soon learns that Carla and Cox went on a date before Turk came to the hospital.^[13]

Despite his contempt for Turk in early seasons, Cox develops a restrained level of respect for him, and even occasionally gets along with and relates to him. In the Season 6 episode, "My Road To Nowhere", when complications are found with his unborn child he insists that Turk assist with the surgery. Being reluctant at first, he even appoints Turk as the Chief Surgeon of Sacred Heart. Cox makes this decision after being told by Kelso that his own promotions by Kelso were against the latter's personal disdain for Cox, yet Cox's excellent medical knowledge made him the best candidate nonetheless - a feature that Turk shares with Cox.

He berates Elliot almost as much as J.D., frequently making fun of her insecurity, hairstyle and WASP background. However, he has also been known to stand up for her: he punches Kelso in the face when he yells at her in front of the staff.^[3]

Cox despises Kelso, Sacred Heart's chief of medicine. They disagree constantly about the best way to provide care, with Cox advocating for patients and Kelso adhering to the hospital's bottom line. At one point, he even punches Kelso in the face.^[3] On occasion, however, they have acknowledged the necessity of the other's position, and Kelso has admitted that they need each other.^[12] When Kelso retires and Cox succeeds him as chief of medicine, Cox confides in him about the pressures of the job, and the two form a "secret friendship".^[14]

While Cox has had limited interactions with veteran nurse Laverne Roberts (Aloma Wright), his cynicism drives him to mock her strong religious beliefs on occasion. This culminates in Cox confronting her about a seemingly "miraculous" accident, unwilling to accept it as divine intervention. Visibly upset, Laverne replies that after 24 years as a nurse, she has to believe in a "bigger plan" or she would lose all hope. Taken aback, Cox uncharacteristically apologizes and sincerely replies that he wishes he could also believe that.^[15] When she dies in the following episode, he joins the rest of the staff in bidding her farewell and drinking in her honor.^[16]

He berates J.D. from their first meeting^[17] and emphatically denies being his mentor, despite J.D.'s repeated attempts to win his favor. Nonetheless, Cox has shown concern for J.D.'s welfare, such as telling him not to blame himself for a patient's death^[11] and (reluctantly) comforting him when his father dies.^[18] He also tells J.D. that he trusts him as a doctor and a person and has taken an interest in him from the start because he seems "to actually give a crap".^[19] Cox also recommends him as a promising, skilled, and hard-working doctor to a review board.^[20] In "My Finale", Cox finally admits that he considers J.D. a talented doctor, a good person, and a friend, although he has to be tricked into it. He refuses to say this directly to J.D. or to hug him. A flash-forward scene at the end of the episode suggests that Cox will be a part of J.D.'s life well into the future (reluctantly, of course).^[21]

In the ninth season, Sacred Heart has become a medical school, and Cox is hired as a professor. He immediately begins berating the series' new protagonist, Lucy Bennett (Kerry Bishé), and takes an interest in one of his students, Drew Suffin (Michael Mosley). He calls the latter "Number 1" and makes him his protégé, much to J.D.'s chagrin.^[22] However, he still provides advice and support to J.D. (albeit in his usual sarcastic fashion) by telling him that he has to learn to let his students make their own mistakes.^[23]

Family life

Cox's family is from Pittsburgh. He has a sister, Paige (Cheryl Hines), who is a born-again Christian.^[24] Cox is presented as an ardent skeptic^[24] who says that he does not "technically believe" in God.^[25] His political views are varied; he has expressed disdain for members of both political parties, as well as "registered Independents". He opposes the Iraq War and is disgusted when Elliot reveals that she is a Republican.^[26] He also uses "Republican" as an insult for Paige.^[24]

Cox's father was an alcoholic who regularly beat him and Paige, and Cox later says that his mother did nothing to stop him when he "drunkenly knocked us from room to room". At the end of one episode, he admits to his sister that seeing her reminds him of the childhood he has tried so hard to forget.^[24]

Cox was apparently legally divorced from Jordan Sullivan (Christa Miller Lawrence), but the two have lived together in an exclusive relationship since Jordan discovered she was pregnant.^[27] The marriage appears to have started out strongly, but went downhill after Jordan cheated on him with Dr. Peter Fisher (Jay Mohr).^[28] They were originally to have divorced after their first child died in infancy, but this plot point was omitted because the network decided that it was too dark a twist in the story.^[29] Later in the series, it is revealed that Sacred Heart's incompetent lawyer Ted Buckland (Sam Lloyd) did not submit the divorce papers properly, so Cox and Jordan have been married during the entire run of the show. They immediately resume the role of husband and wife since they have already reconciled, but they quickly become dissatisfied with being an ordinary married couple, so they agree to go back to acting as though they were divorced, even going so far as to actually legally divorce, with Ted (again) ending their marriage. In later seasons, Cox quietly resumes wearing his wedding ring, and Jordan soon acquiesces to the marriage title after the birth of their second child, and it is implied that they have remarried.

He has two children with Jordan: a son named Jack and, after an unsuccessful vasectomy, a daughter named Jennifer Dylan (J.D.). Jack is played by Andrew Miller and his twin brother (although in a cameo appearance in "My Missed Perception", he is played by Bill Lawrence and Christa Miller's son, William). When Jordan first becomes pregnant with Jack, she tells Cox that she was impregnated by a Greek bellboy, wanting Cox to stay because he wants to rather than out of obligation to his child.^[27] At first, Cox feels nothing for the then-nameless boy, but begins to feel a connection after the child responds to the name Jack, which Cox had been trying to impress upon him for some time. J.D.'s college friend Spencer (Ryan Reynolds) accidentally tells Cox that he is actually Jack's biological father,^[3] and he takes on the role of father much more seriously. Cox has a very unorthodox way of raising Jack, often treating him like his "drinking buddy". Nonetheless, Cox loves his son and tries fervently to be a better father than his own was. He often talks to Jack in lieu of a therapist. He also dotes on his daughter; among other things, he goes far out of his way to have someone else give her a shot so that she will not associate him with pain.^[30]

Cox is best friends with Jordan's brother, Ben (Brendan Fraser), and is hit hard when he is diagnosed with leukemia; he is initially too afraid to treat him because he fears he will lose him. He rallies, however, and helps Ben go into remission.^[31][32] Ben dies in the episode "My Screw Up", but Cox convinces himself that he is still alive. When he finally admits that Ben is dead, he is devastated, and uncharacteristically allows people to comfort him at the funeral.^[33]