<P> DeFer was promoted to series regular for the fifth season in light of cast members Taylor Momsen and Jessica Szohr's departure . She is the newest addition to the female cast of Gossip Girl villains, joining the likes of Georgina Sparks and Juliet Sharp . </P> <P> Introduced in the fourth season, DeFer was set to join the cast as Carol's daughter and Serena and Eric's cousin, Charlie Rhodes . DeFer's contract with the show also included the possibility of her becoming a series regular for the fifth season . She first auditioned for the role of Raina Thorpe . However, that role went to Tika Sumpter . DeFer was called back for the role of Charlie Rhodes, with the show's writers stating that they were writing something new for her character . DeFer had also previously worked with Gossip Girl executive producers, Stephanie Savage and Joe Lazarov as well as Penn Badgley in The Mountain . </P> <P> Executive producer Joshua Safran later commented on her introduction and the perception that the character brought to the show . "We always like it when we have new people who are witnessing this world for the first time...For Charlie, it's like trial by fire . From reading Gossip Girl for the first time or going to your first event, all that stuff we get to do over again in a new way ." </P> <P> Charlie's integration also made her a voice for the audience and critics of Gossip Girl . TV Fanatic warmly welcomed her character, stating that she "good - naturedly mocked the show and its often convoluted plot lines ." DeFer would later reveal details behind her character's involvement in the fourth season finale, "As far as I know I'm just in the next five episodes until the season finale, and then I have no idea . But I really hope we get the opportunity to finish what Charlie started as I think it's going to be a story - line that people will really want to follow ." DeFer also states that Charlie is more relatable in comparison to other characters that have appeared in the show . "She is such a real person, not being from that life and what not ..." </P>

When does serena find out who charlie is