"You let me grow the hell up," Karev admits to Bailey in his letter to her. He explains that unlike all of his other teachers, Bailey gave him crap when he needed it and helped him become the man he is today. (Barring the whole situation where he left everyone that meant the world to him with only letters to say goodbye.) He admits that he could never repay Bailey for all the things she taught him, noting that "you kicked my ass and asked more of me more than anyone." He attributes his growth into an amazing surgeon and an "okay guy" to her, while also breaking her brain by revealing that he's left to take care of his twins with Izzie. "Goodbye and thanks," he ends his letter. "I love you, Dr. Bailey."