It's a bit unclear which types of undead are playable. Seems like the clearest case is you can play a Raised One that has broken away from his necromancer. But then, will you slowly become a faint one as the necromantic power fades from you (constantly having to recharge yourself with source, or something like that)? Or perhaps you can play a Chosen one from the start that has been exiled or has run away or something. Definitely a lot of potential for various origin stories; not sure if they'll be able to have more than one.