Grey's Anatomy

Much of Addison's past is presented in a non-linear fashion, primarily revealed in the second and third seasons of Grey's Anatomy and the second season of Private Practice. Addison is the daughter of wealthy parents, and has a twenty five million dollar trust fund. Her mother, Bizzy Forbes Montgomery, is rarely referred to as "mom" while her father was frequently adulterous and used time spent with Addison as a pretense. Her brother Archer is a world-class neurologist and successful author. Addison met her future husband, Derek Shepherd, at medical school; she met future colleagues, Sam and Naomi Bennett, there as well. She completed her residency under the supervision of Richard Webber. Addison, along with Derek, became successful in their respective fields and each began their own practice in New York, which placed a strain on their marriage. Addison's affair with Derek's best friend Mark Sloan prompts the end of their marriage and Derek's departure to Seattle. Addison briefly attempted to have a relationship with Mark, which resulted in her becoming pregnant. She had an abortion as she was still in love with Derek, and when Mark cheated on her, she moved to Seattle.

Addison first appears in the season one finale, arriving at Richard's doing. She immediately learns that Derek has started a relationship with intern Meredith Grey, and tries to reconcile her relationship with him. Derek is initially still angry with her, and there is a period of antagonism between them. Addison's presence, however, does reinvigorate their relationship, and ultimately Derek chooses Addison over Meredith. They attempt to return to their former life, taking residence in his trailer, and Addison makes her move to Seattle permanent, becoming the head of a unique surgical service integrating neonatal surgery and obstetrics and gynecology. She begins to realize that Derek still has feelings for Meredith, and their marriage is tested further when Mark arrives in Seattle looking for Addison. When Addison finds out about Derek's affair with Meredith, she gets drunk and pursues a relationship with Mark that ultimately fails. During season two, Addison punishes Alex Karev by putting him on her service. However, by season three, she begins to feel attraction towards Alex and eventually sleeps with him, only to discover that he is not interested in a relationship with her. Feeling alone, Addison decides to have a baby and visits Naomi, who is a fertility specialist. This introduces Addison's transition from Grey's Anatomy to its spin-off, as it serves as the backdoor pilot for Private Practice. Soon after, Addison decides to leave Seattle and move to Los Angeles, joining Oceanside Wellness, led by Sam and Naomi. This marks Addison's depature from the series as a regular.