GREY'S ANATOMY - "Sympathy for the Devil" - Derek's mother, Carolyn, suspects Mark is hiding something and convinces him to admit to having an affair with Lexie Grey, on "Grey's Anatomy," THURSDAY, JANUARY 15 (9:00-10:01 p.m., ET) on the ABC Television Network. (ABC/RANDY HOLMES) TYNE DALY, ERIC DANE