Blair is married to Dan and is not happy, she will work in the Bass industries and fall in love with Chuck. The story is classified as "M".
I do not remember many other relevant details, but Serena and Blair still do not know each other, Nate is Jenny's boyfriend and Serena's ex, Chuck and Serena are brothers, Chuck dates Vanessa but ends up with her, Serena goes crazy to be friend of Blair.