Okay, since someone asked, and I can't fit it all in one post, here's a DF demon based civ, which I built for a potential community/succession fortress idea. It's currently rough, but works.

So far, it's just the race, which consists of a minotaur-copy base 'daemon' and several castes that are copies of procedurally generated demons I stole from a world I genned. These have only really been tested in the arena, and they survive worldgen with a copy of the goblin civ raws. I do plan on giving them a little more structure, and properly sized equipment, as well as their own metal, but that will be later.