User blog comment:Saikou The Lewd King/Paradox list of AUs/@comment-2037710-20160523094540/@comment-25707465-20160523182348

Or maybe the ancestors come from an existing verse where they sealed themselves to stop the Great Monster War. However, they may have always been slightly sadistic, and it may no have been helped by thousands of years of isolation.

It's possible the Lilith sisters followed the same fate.