Maggie Pierce

Margaret "Maggie" Pierce was hired as head of Cardiothoracic Surgery at Grey Sloan Memorial Hospital after Jeff Russell quit. Shortly after starting work, she revealed to Richard Webber that Ellis Grey is her birth mom.

Education
Margaret is very driven and finished both high school and medical school faster than normal.

Search for her Birth Mom
Two weeks after she was hired as head of cardiothoracic surgery at Grey Sloan Memorial Hospital, Margaret told Dr. Richard Webber that she was adopted, and that 2 years prior, she looked for her birth mom and needed to go to the court for the records. She found out that she was dead, but got her name, and discovered that she was an amazing surgeon that worked at the Seattle Grace Hospital, now Grey Sloan Memorial Hospital, Margaret's current workplace. She stated that that's not why she took the job, but it's "a little bit" why she was interviewed. When Richard asked Margaret what her mother's name was, she said that it was Ellis Grey. ("Fear (of the Unknown)")

Working at Grey Sloan Memorial
Maggie quickly began to integrate into the hospital, getting to know everyone and how things work. However, she butted heads with Meredith Grey over a case. This came to a head when Maggie told Meredith that Ellis Grey is her birth mom. ("Puzzle With a Piece Missing")

Parents
She describes her parents as good, funny, kind, and goofy.

Ellis Grey
Margaret never met her birth mother, but 2 years prior to joining the Grey Sloan Memorial Hospital staff, she looked for her birth mother and found out that she was dead, but got her name.

Cristina Yang
Cristina and Margaret first met when Cristina interviewed Margaret for the head of cardio position at GSM. Despite feeling that Maggie was very young to do the job, she admitted to Owen that she was qualified to do it.

Once she was officially hired, Margaret became frustrated because Cristina didn't respect her as her new boss. On Cristina's last day, she scheduled a pediatric heart transplant (for Link McNeil) amidst the chaos of the explosion at the mall, much to Maggie's confusion and frustration. Cristina even treated her as a resident by not listening to her objections and practically forcing her to prepare Link for the surgery. Margaret ultimate did the transplant herself as Cristina had to leave to catch her flight.

Richard Webber
Maggie quickly bonded with Webber while they worked together. She admired his skill greatly. When he eventually tried to tell her that he's her biological father, she became upset with him for having not told her right away.

Career
She is the new Head of Cardiothoracic Surgery at Grey Sloan Memorial Hospital.

Notes and Trivia

 * She finished high school and medical school early.
 * In the episode, Fear (of the Unknown), it is revealed that her birth mother was Ellis Grey and therefore, Meredith Grey is her biological maternal half-sister.
 * Her biological father is Richard Webber.
 * The writers stated they knew about Maggie's existence since the very beginning and wanted to introduce the character ever since season 4, but chose to introduce Thatcher's other children first; afterwards, it never felt like the right time until Cristina left, creating a hole in Meredith's life. This also led Shonda to claim that there have been indirect references to Maggie over the course of the series.
 * There's nothing Maggie doesn't eat.
 * On Twitter, Shonda Rhimes revealed she thought a lot about making Ellis and Richard's love child a son. She even looked for an actor, but decided to settle for Kelly McCreary's acting talents, as the actor's great acting skills were more important to her than the actor's sex.
 * Her salary is $126,000/year.
 * Her employee ID number is 6654.
 * Her work email address is mpierce@greysloan.

Notable Episodes
These episodes are Maggie-centric or are otherwise very informative about her life.
 * Fear (of the Unknown)
 * Puzzle With a Piece Missing

Memorable Quotes

 * Maggie: You think I look too young. I finished high school early, also med school. Pretty annoying, right?