In this photo from "The Thin Line Between Chuck and Nate," Serena flashes a brilliant smile. And why not?! She's pretty, has a great boyfriend and is really turning her life around.
Eleanor: Are you all right? Blair: Never been better. Eleanor: Well, Serena has. What's wrong? Blair: I don't know. I can't be held responsible for her mood swings. Eleanor: Were you arguing about the possibility that your condition may have returned. Blair: No. It hasn't. Eleanor: I heard you the other day in your bathroom with the water running. Blair: I'm very stressed. And with you and Serena down my throat I can hardly see straight, never mind keep food down.