User blog comment:Saikou The Lewd King/Paradox list of AUs/@comment-2037710-20160523094540/@comment-26441687-20160523163253

I doubt Alice stopped Beelzebub out of any sense of compassion, more like just to protect the balance between humans and monsters.

If the Lilith sisters and the ancestor descriptions are any indication, they definitely don't seem to have any respect for human life, but that doesn't mean they kill or slaughter them senselessly. It's in their best interest to keep humans alive after all. I'd wager that they probably just have a more elitist "humans are lesser than us" attitude than monsters in the present.

Of course that's just speculation since we don't see that universe. It's possible that the ancestors and the Lilith sisters are just exceptions to the general population. Also the way the Lilith sisters talk make it seem like they come from a time period long ago that's still close to the great war so I think naturally when you take people from a period where they're fighting a war they're going to be a bit... rowdier than from a period of peace.