The rest of the morning makes little sense as her mother tries to explain that the families have struck a deal in which Blair in her good fortune and generosity will train with Dan for the Cotillion. "Why not have Serena do this with him? He's going to be her escort." "Serena hasn't agreed to go yet and her grandma wants to surprise her with this development." Typical. Blair's hard work becomes Serena's magic. Dair Fanfic. Set 1x10.