[@Dusty] Well my plan is for everyone to start in Ba Sing Se and meet up from there (Of course you can join up later if you prefer). In terms of why, that's up to you, there'll be some people paying for information on the Avatar so some might join the quest for monetary reasons, some might not want to see Warlord An gain too much power and want the Avatar, some might just be fascinated by the Avatar, plenty of options.