Blair's 20th birthday was the big event in episode 7 of season four of Gossip Girl. Called "War at the Roses" Blair and Chuck call a truce, even having a notarized treaty being drawn up. In the opening scene, Blair (Leighton Meester) is seen wearing Alex Woo's Little Signs Scorpion. Having had enough of Chuck (Ed Westwick) and Blair's games, Serena (Blake Lively) and Nate (Chace Crawford) decide to plan an intervention. Musical guest Robyn performs in the episode. Penn Badgley, Taylor Momsen, Jessica Szohr, Kelly Rutherford, and Matthew Settle also star.