Arizona Robbins is the current Head of Pediatric surgery at Seattle Grace Hospital, following the death of the previous Head of Department, Dr. Jordan Kenley. She is also girlfriend to Callie Torres.

Season Five

Following the death of Dr. Jordan Kenley (John Sloman) of a heart attack during an examination of one of his patients, Chief Webber replaces his head of pediatric surgery with Dr. Arizona Robbins, who graduated top of her class and was chief resident during her residency. She is initially disliked by Miranda Bailey (Chandra Wilson), who disagrees with her treatment of a patient, however after seeking a second opinion, Bailey realizes that Arizona is correct. Working alongside Arizona, she later develops an interest in pursuing pediatric surgery as a specialty.

Arizona has a romantic interest in orthopedic resident Callie Torres (Sara Ramírez), and kisses her in the episode "Beat Your Heart Out". However, when Callie asks her on a date and mentions that it would only be her second relationship with a woman, Arizona declines due to her inexperience. She later apologizes, and asks Callie to dinner. The two begin dating, but when Callie's father (Héctor Elizondo) learns of the relationship, he threatens to cut her off financially unless she returns home with him. Callie refuses to leave Seattle or Arizona, sacrificing her relationship with her father. Callie struggles to adapt to the loss of her family and trust fund, and briefly contemplates lying that she and Arizona have broken up. Although Arizona states that she will support Callie whatever she decides, Callie ultimately opts not to deny their relationship. Callie comes close to breaking up with Arizona as she struggles with her new financial restraints, however they later reconcile and sleep together for the first time. When Callie's ex-husband George O'Malley (T.R. Knight) announces his intention to join the US Army and leave for Iraq as a trauma surgeon, Arizona is the only staff member to support his choice. Callie is initially angry, until Arizona explains that her brother was a soldier and died in Iraq. Arizona tells Callie she loves her in Season 6, episode Invest in Love, and Callie says she loves her as well.

Season Six

When Callie's father returns to Seattle and continues to reject his daughter's sexuality, Arizona is able to convince him to reconsider. She explains that her father and grandfather were both in the military, and that she was named after the USS Arizona which sunk in the Pearl Harbor attack, during which her grandfather saved nineteen lives before drowning. She tells Mr. Torres that her father was able to accept her own sexuality as she promised him she was still the "good man in a storm" he raised her to be, and that Callie is still the same person he raised.