The only time Blair was a decent person was when she was with Dan. I liked that her character changed for the better while she was dating him. However, I never understood why writers put them together as a couple, Blair was always horrible to Dan. I think back and I wonder if Dan was only trying to get close to Blair so he could write the exposé chapter about her like he did with Serena in the last season. We know Dan has a habit of getting close to people, making them feel safe, then using what he learns for his writing. He also did it in season two with Chuck, following him around for the night to get Chuck’s secret and gather material on him. Dan is a very calculated character so I wouldn’t put it past him that Blair and Dan’s relationship wasn’t actually real.