S2, E4: As Cristina tries to recover, she proves to be a very difficult patient, and a visit from her mother doesn't improve her demeanor any. And Meredith's mother, Dr. Ellis Grey, has the hospital staff running in circles. Jeremiah, a cystic fibrosis patient, could benefit from Dr. Addison Shepherd's medical knowledge, but her involvement in his surgery could delay her highly anticipated departure from Seattle Grace Hospital, leaving Meredith and Derek's relationship hanging in the balance.