GREY'S ANATOMY returned on Thursday night with two new episodes. Over the 9-11 p.m. ET two-hour block, the show won the adults 18-49 demo with a 4.1 rating and 10 share. CBS dramas PERSON OF INTEREST and THE MENTALIST had about 3 million more viewers (GREY'S had 10.38 million).Meanwhile on The CW, THE VAMPIRE DIARIES scored an A18-49 1.2 rating (3 share) and 2.52 million viewers. THE SECRET CIRCLE was watched by 2.12 million with a 0.9/2 demo. Both shows were down from last week facing premieres on CBS, NBC and ABC this week.