Callie Torres is introduced as an orthopedic surgery resident with a crush on intern George O'Malley (T. R. Knight). The two start a relationship and Torres moves into Meredith's house. Uneased at the way their relationship is progressing, O'Malley confronts her, which results in her moving into a hotel. In the aftermath of the breakup, she meets and has a one-night stand with plastic surgeon Mark Sloan (Eric Dane), who becomes her friend. Torres and O'Malley subsequently reconcile, and the two marry in Las Vegas on the spur of the moment. Confused, O'Malley confides to fellow intern Izzie Stevens (Katherine Heigl), about his relationship woes over alcohol, leading to a drunken sexual encounter between the two. Torres remains unaware of his sexual encounter, but becomes increasingly suspicious, and announces her desire to conceive a child. Shortly thereafter, however, she discovers that O'Malley has been unfaithful, ending their marriage. Though her personal life is troubled, Torres thrives professionally when she is appointed as the hospital's Chief Resident. However, she soon begins struggling to cope in the role, and is demoted soon thereafter.