Gossip Girl episode 2

In this episode Blair tells to Serena that she knows the reason why she left New York and tells her that they aren't friends anymore. Then Dan hangs out with Serena to Chuck's lunch. In there Dan sees Serena's mother with Chuck's father, he discovers that they have something. 
Nate tries to talk with Serena about what happened between them, he tells Serena to meet him in Chuck's hotel room, but then Blair finds Serena waiting for Nate there.
Then Chuck insults Dan's sister and Dan hits him in his face. Then Blair tells him the past about Serena and he walks out, Serena tried to follow him but he told her to not do it.