Theoretically any lemure could become the next lord of nessus, pratically most will never advance very far.Don't all of the evil cosmologies have the prospect for rebirth and possible later ascension? I thought lemures and the like eventually reform and get another chance to work their way up to pit fiend.
And while they are on the bottom, anyone above them is being a dick to them.
Likewise on Celestia it's not that different in regards to advancement, but everybody above you is comoassionate and helpful toward you.