Talk:Demon Lord/@comment-25217644-20141111005246/@comment-12776-20141111145628

Or they could be the last remnants of monsters who still follow prevous Demon Lord ways.

How? Even Youkai which are NOT part of Demon Lord Army were effected by Demon Lord's "reprogram" and become women, so I don't think normal monster even has a chance to resist it.

the violent, soul-sucking, blood thirsty ones protrayed in some fantasy world

"Some fantasy worlds" has nothing to do with MGE world, and no-kill policy come along with transformation, so it doesn't matter.

So far, the only type of "monster" may be able to resist Demon Lord's transformation are those Demons of Chaos in the deep ocean, and that's because it's said that they were more powerful than gods.

In other words, your idea has no place in official setting.

Back to question, I think they just turned into succubi. Unlike current incubi, they're full demons, not men with demonic power, and so it make sense that they changed along with all other demons back then.