Episode 3x5152 THE FRESHMEN
Blair, determined to maintain her Queen Bee status in college, embarks on her first day at NYU, along with Dan and Vanessa. Unfortunately, Georgina (recurring guest star MICHELLE TRACHTENBERG) turns up as Blair's roommate in the dorms, determined to make Blair a social outcast. As Serena prepares to depart for Brown, she and Chuck have a major falling out, so she recruits Chuck's enemy, Carter (recurring guest star SEBASTIAN STAN), to help her get even. Meanwhile, Nate and Bree (recurring guest star JoANNA GARCIA) decide to explore their relationship further, knowing full well it could cause tension between their families who are political rivals.