Lexie feels immense guilt following George's death, having abandoned their friendship after he failed to reciprocate her romantic feelings towards him. She is consoled by Mark and, after becoming a surgical resident, agrees to move into his new apartment with him. Lexie and the other residents grow increasingly stressed in the wake of Chief Webber's announcement that there will be an administrative merger with Mercy West Hospital, meaning that Seattle Grace will have to layoff a large portion of its staff members. Mark encourages Lexie to relax and just try her best during this period, advising her not to worry as she deserves her job. Lexie soon finds that while she is safe from the layoffs, many of her friends have been cut from the program. To take everyone's minds off the merger, Owen takes Lexie, Mark, Derek, Meredith, and Cristina to play baseball together. Thatcher is later admitted into the hospital with liver failure stemming from his former alcoholism. When Lexie discovers that she is not a suitable transplant candidate, Meredith steps in and donates part of her liver to Thatcher to spare Lexie the grief of losing her father. Following the merger, Lexie develops a rivalry with Mercy West resident April Kepner (Sarah Drew), who desperately attempts to undermine Lexie while they are both on Derek's service. Lexie retaliates by stealing April's notebook and using its personal contents to humiliate her, though Lexie later apologizes. When a patient dies from a medical negligence mistake committed by one of the many surgeons who treated her, Webber starts a witch hunt to trace back the culprit and identify the cause of death, and Lexie is among the doctors who are questioned; it is ultimately discovered that April was the one at fault.