Erica Hahn

Erica Hahn is a cardiothoracic surgeon who briefly worked at Seattle Grace Hospital and dated another employee, Callie Torres. She previously worked at Seattle Presbyerian Hospital and attended JohnHopkins where she started a fierce rivalry with Preston Burke.

Childhood and growing up
When Erica was a child, she had continuous headaches, she went to the doctors and was told she needed glasses, it made no sense to her but on the car journey home, she shrieked because the little green blobs she had been seeing all her life were actually leaves, and she didn't even know she was missing them.

Personal life
Erica Hahn presents herself as a confident woman, generally focused on her work and not afraid to speak her mind when she sees it right. Early in her time at Seattle Grace, when word was being passed of a "Gentleman's evening" planned by the Chief of Surgery to which only the male attendings were invited, Dr. Hahn grilled Dr. Webber on the lack of professionalism of such an event, likening it to the not-so-distant era of racial discrimination. Later in the evening, she crashed their party and beat them at monopoly. Though generally slow to make friends, Erica befriended Callie, seeing in her a strong woman and also another loner. At roughly the same time, she became friends with Mark and Addison when Addison came to visit (although she still had a slight dislike for Mark).

She had a rough relationship with Cristina Yang, consistently denying her the privilege of sucking up, and making her fight her way to stay on the cardio program. Her first day at Seattle Grace, Erica made it clear that personal and professional life would be separate things, telling Cristina "if you had the chops in the operating room, you wouldn't need to impress in the bedroom", referencing Cristina's tendency to have relationships with her former teachers. This harsh attitude didn't go unnoticed. During her brief visit, Addison witnessed some of Hahn's hostility and asked why she was so closed to Cristina. Hahn then admitted to her that Cristina reminded her of herself when she was younger. Richard Webber noticed this tendency of Hahn to shut Cristina out, and insisted that she be a better teacher, causing her to reevaluate her professional technique. Hahn also maintained a tough edge with Bailey, refusing to operate on Bailey's son while she was in the room and staying negative during a complicated surgery when Bailey was trying to save a girl's life.

Although originally taking a liking to her, Erica disliked Izzie strongly after discovering that Izzie had been the root of the cause behind one of her patient's losing out on an important heart transplant, due to Izzie's relationship with Denny Duquette. Though generally emotionally detached, Dr. Hahn is indignant at the unfair treatment to her patient, a good man with kids whose chance was taken away. She was not able to recover from the seemingly personal nature of this attack, to which neither the Chief, the hospital, nor Callie would see her side or come to her defense, one of many causes of her eventual break with the hospital.

Romantic life
When Dr. Hahn took up a permanent position at Seattle Grace, one of the first things she said to Cristina was I sleep with men (believing that Cristina got ahead by sleeping with her superiors). Mark Sloan continually flirted with her but although they were friends, she insisted that he only wanted her because he couldn't have her, though admitting that they might have had a chance if they didn't work together.

After making a friend of Callie Torres and getting more involved personally, onlookers became suspicious of a bit more to their relationship. Addison Montgomery plants the seed in Callie's head that the two might be lovers, but when confronted, the both laugh it off, though the idea lingers. Following Mark Sloan's persistent, (if only half-joking) suggestions of starting a threesome, Erica asks Mark whether the idea of her and Callie in a relationship would be intimidating to him, and kisses her in the elevator to prove it. A conflicted Callie can't get Erica out of her head, and the two finally confront their feelings and uneasiness about the "new territory", and begin to date. Though both share feelings for each other, Callie and Erica react to the blossoming relationship in different ways. While Callie is unsure what the relationship means for her and her sexuality (still enjoying her sex life with men), after a few nights spent with Callie, Erica realizes that she must be gay, though she admits to relationships with men in the past. For Callie, Erica's revelation makes her nervous and sends her running to Sloan for sex, twice in one day, where she finds the chemistry just as good. Though Callie's bisexuality is not necessarily a failure to commit, Erica is hurt by what she sees as "grey area" in the relationship where she would rather have straight answers. She claims "you can't be kind of a lesbian" and walks away from Callie and Seattle Grace, having lost her only personal ally.

Career
Dr. Hahn is a long-time rival of Dr. Preston Burke in the field of cardiothoracic surgery, dating back to their days at Johns Hopkins Medical School, where she graduated second after Burke. She was a cardiothoracic attending surgeon at Seattle Presbyterian Hospital.

In Season 2, she and Burke fought over a donor's heart (who appeared much later in Season 5) because of faulty information from Izzie pertaining to Denny's condition, and she was contacted for a consult on Harold O'Malley's valve replacement.

Hahn joined the staff of Seattle Grace Hospital in the Season 4 Halloween episode, "Haunt You Everyday", after performing a heart transplant at the request of Chief Richard Webber. As such, she became Head of Cardiothoracic Surgery at Seattle Grace and appropriately dubbed "The New Burke". She left the hospital following the revelation that Izzie was not ever truly punished for what happened with Denny Duquette.