They'll be "main characters" but right now secrecy surrounds them. Some of the original cast from Final Fantasy XIII will be returning for the sequel.
The development staff of the first ever Final Fantasy sequel title remains largely the same as those involved with the original Final Fantasy XIII. Noel is the lead character for XIII-2 and is a young man with a thing for saving damsels in distress it seems.
Isamu Kamikokuryo revealedabout Final Fantasy XIII-2's development in an interview with Japanese magazine Famitsu - mainly art work related. Final Fantasy XIII-2 releases on Xbox 360 and PS3 in early 2012, this winter in Japan.