Yay! I love their friendship/frienemyship/whatever you want to call it:D I wasn't sure if anything specific had been decided regarding the 'real reason' Serena left New York but that's always something that can come up in the future!
That and just trying to work through their friendship which'll probably be a constant roller coaster. Especially with the premise of the game, Serena is probably more inclined to slide back into her old ways more easily and Blair's an awesome for slapping her back into place.