S3, E6: Vanessa, hoping to finally win the approval of her mother, Gabriela (guest star GINA TORRES - 24, Alias, Firefly), desperately vies with Blair for the honor of delivering the freshman toast at NYU, but at what price? Dan invites Olivia (recurring guest star HILARY DUFF) to meet Rufus and Lily, which leads to all sorts of problems for the new couple. Serena and Nate team up to help Carter Baizen (recurring guest star SEBASTIAN STAN).