2x19 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 lifestyle with Carter by her side. Causing Serena and Chuck to have serious concerns about their friend and team up to take him down. 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, which causes Nate and Vanessa to have problems. In a misguided effort to be completely honest with each other, Lily and Rufus agree to share lists of their past lovers. Nate and Blair have a heart to heart talk changing the way they see each other.