GREY'S ANATOMY - "Superfreak" - When Derek receives an unexpected and unwelcome visit from his estranged sister, Amelia, issues between the siblings -- both past and present -- come to the surface; the Chief tries to help Alex when he notices that he's refusing to use the elevators after his near-fatal shooting; and Meredith and Derek continue their efforts to ease Cristina back into surgery after her post-traumatic stress, on "Grey's Anatomy," THURSDAY, OCTOBER 7 (9:00-10:01 p.m., ET) on the ABC Television Network. (ABC/DANNY FELD) JUSTIN CHAMBERS, SARAH DREW