Charlie's objective is revealed; she wants to have Serena's life, or well, be Serena. She shows up to Blair's party wearing S's cotillion dress (even I remember that dress, because I loved that episode), and Serena gets angry and creeped out that Charlie stole her dress. Their fight escalates until Dan declares that he and Charlie are leaving, and he's on crazy cousin's side at the alumni event. That is, until they have a sexy interlude and mid-foreplay, Charlie requests that Dan call her Serena. It's enough to stifle Dan's libido and make him start to panic, while Rufus simultaneously discovers that Charlie hasn't been taking her meds.