Justin, who is being adopted by the Jensens, becomes involved with his mother's old drug-dealing lover, Seth. By the end of the season, Justin had broken up with Jessica by telling her he had cheated on her, despite the fact that he was attempting to conceal his drug use. Later in the series, it is revealed that Justin was using marijuana during filming of the show to help him write lines. He later admits to having an addiction problem and decides to enter a rehabilitation facility. His father, John, feels that this is a bad idea because drugs will only hold him back from moving forward with his life. However, Justin decides to go ahead with his treatment anyway. During this time, it is also revealed that Seth was responsible for Justin's adoption, as well as another child who shares a birthday with Justin. It is suggested that he used this information to blackmail John into giving him money. After going through rehab, Justin decides to move forward with his life. He gets a job as a writer's assistant at a television studio where many popular shows are created from ideas by staff writers. He meets and begins dating one of the most powerful women in television, Robin Arnor, who has her own production company. They eventually marry in order to save her career. After marrying Robin, Justin learns that she has been hiding a secret marriage license from her first husband, who she married when they were both 19 years old.