For factions, I'm thinking of either: 
-An order of scholar-warrior-priests who venture out of the haven of the Oasis states to unearth artifacts and knowledge about Nabushan pre-Calamity 
-Mercenary group the scalps of a particularly hated xeno group in the Great Wastes 
-A maritime city-state made entirely of reconstituted vehicles/detritus that exacts tolls on other states to gather their water 

Not sure about a character yet