The reason Dan wrote the positive chapter about Chuck? He was messing with Blair's head and trying to make her insecure. He wants her to think Chuck will never be done fighting with Bart. I hate the stupid pact as much as the next person but Dan wasn't right at all about Chuck and Blair. Chuck and Blair will eventually get their happy ending. I didn't think it was possible for me to hate Dan more but each episode he's "Challenge Accepted". This episode he was emotionally manipulating Blair and acting like a second rate Chuck Bass with his bowties and pervy innuendo. I loved when Blair gave him the smack down and told him what a hypocrite he was. Honestly I don't think Dan is hung up on Blair as much as he's obsessed with losing to Chuck. Having said that I don't think he's being sincere with Serena. now. But I think he'll fall back in love with her hanging around her.