After openly acknowledging the shooting as a mass murder during a therapy session with trauma counselor Andrew Perkins (James Tupper) and the other residents, Lexie experiences a psychotic breakdown stemming from PTSD and sleep deprivation while she is treating a patient. She is admitted to the hospital's psychiatric ward, where she is sedated for over 50 hours with Meredith remaining by her side. Alex breaks off his relationship with Lexie because he cannot handle having to care for a person going through PTSD and he enjoys sleeping with women that find having been shot to be attractive. Lexie, after recovering and being cleared for surgery, confronts Alex at Cristina and Owen's wedding and knocks him down a peg by telling him that the reason he is alive is because of her. Lexie becomes irritated when others at the hospital view her as fragile and incompetent due to her breakdown and works hard to repair her image; she saves a woman from being paralyzed when no one else caught the issue. She continues to gain her confidence throughout the season and helps Miranda Bailey (Chandra Wilson) discover a cure for hospital fistula. Lexie's rivalry with April intensifies when the latter begins growing closer to Meredith, but Meredith later assures Lexie that she will always be her sister.