2.19 "The Grandfather"

Devastated by the recent plot twist in her life, Blair turns her back on her predictable Waldorf existence in favor of a wild, unpredictable lifestyle that includes Carter, causing Serena and Chuck to have serious concerns about their friend. Vanessa convinces Nate that it may be time to forgive and forget when it comes to his mother's Kennedyesque family, The Vanderbilts, who abandoned Nate and his mother when they needed them most. Elsewhere, in a misguided effort to be completely honest with each other, Lily and Rufus agree to share lists of their past lovers.