Serena is getting ready to work on another movie. But Blair is still Gossip Girl Seasons 1-5 mad at her for leaking her diary. The season 5 finale started with Gossip Girl leaking Blair’s diary which revealed her deepest thoughts about Chuck.
Blair calls in Penelope to do damage control, and in this case that means getting the scandalous about Serena and taking her down. Also after an entire season of nary a scene between the two former besties, Serena and Blair shockingly exist in the same space at the Gossip Girl Seasons 5 same time.
When Blair gets called back into the scheme she sends Serena in her place to the interview with Dan. Serena gets Dan kind of drunky and then gets him alone and makes her move on him. She says Blair just used Dan to get between them. Serena still wants to be together, but Dan Gossip Girl says he never wants to see her again.