S2, E10: Blair does not approve of new man in her mother's (recurring guest star MARGARET COLIN) life, Cyrus Rose (recurring guest star WALLACE SHAWN - "The Princess Bride," "Kit Kittredge: An American Girl," "Crossing Jordan," "Star Trek: Deep Space Nine," TV's "Clueless"), so she makes it her mission to break up lovebirds by any means necessary. Jenny moves in with Agnes (recurring guest star WILLA HOLLAND) as the friends move forward with their plans for fashion line. Serena continues to fall for the new guy in her life, Aaron (recurring guest star JOHN PATRICK AMEDORI), but she learns something about him that threatens to end things just as they are getting really good. Dan decides to win the trust of Bart Bass (recurring guest star ROBERT JOHN BURKE) in order to learn more about man and possibly write an exposé on him for Vanity Fair, but things get heated after Chuck finds out real reason Dan is spending so much time around his family. Plus, singer CYNDI LAUPER makes a cameo appearance.