Inquisitor sapiens potensque said:
Isn't it heavily implied that Pit Fiends (or whatever they're called) are mutated human beings, the result of the Fenksworld gene atrocity? I would do something with that.
Yes, as well as being suspected to be the survivors of one of the vanished noble houses which was either involved in events, or targeted. There's no clear point as to leave it open for the GM to flesh out and define.
-=Brother Praetus=-