J.D. is the heart and soul of Scrubs as its narrator and main character. He's quirky and often daydreams wild scenarios which are played out in humorous flashback sequences. Through his narration, the audience is privy to his internal dialogue. The first episode of the show is his first day as an intern at Sacred Heart Hospital but by the Season 5 he's an attending physician.

J.D. is a caring and compassionate doctor and patients respond to his kind demeanor. His mentor is the often abrasive Dr. Cox, whom J.D. admires despite the fact that he is constantly under attack by him. Through much of the early part of the series J.D. lives with his best friend Turk, who also works at the hospital, and shares an on-again off-again relationship with Dr. Elliot Reid.