 The season four premiere introduces several new interns, to be trained under Meredith, Yang, Karev, Stevens, and eventually O 'Malley. Among them are Dr. Steve Mostow (Mark Saul) who continues to make appearances, and Dr. Sadie Harris (Melissa George) who formed a friendship with Meredith while the two were in college. Harris is fired in the fifth season, due to not actually having a medical degree, and departs the show immediately after. Meredith and Shepherd's relationship reaches a toll, and the two separate, leading Shepherd to entertaining a relationship with Rose (Lauren Stamile), a nurse. Rose appears frequently until season five, when Shepherd rekindles his relationship with Meredith. Throughout the fifth season, Stevens experiences full-out hallucinations of Duquette, signaling that she is ill, and once she is lucid, he departs, marking his final appearance. Following the announcement of her relationship with Robbins, Callie's father Carlos Torres (Hector Elizondo) initially contests his daughter's concurrence in homosexuality, but eventually accepts it, and he reappears several times throughout the series.
