S1, E6: Dan is torn between two girls when his childhood friend, Vanessa (recurring guest star JESSICA SZOHR), returns home and declares her feelings for him, just as he and Serena are trying to figure out what they mean to each other. At her infamous masked ball, Blair sends Nate on a scavenger hunt, but he is still distracted by his feelings for Serena. Although Blair makes it perfectly clear that outsiders are not welcome, a disguised Jenny and Dan sneak into the ball. Meanwhile, Lily asks Rufus to accompany her to an event hosted by Blair's mother in order to make Chuck's father, who brought a model ("America's Next Top Model" winner CARIDEE ENGLISH) as his date, jealous.