La Vaswald

She was created for the role of serving as an agent of destruction that would annihilate the Protagonist Race if in the case that pollution of Souls became too high and could become troublesome for the Reincarnation Cycle. However, as this event never even came close to taking place, she was deemed worthless and the Supreme Gods Planner and Roven Pan split the goddess into two angel knights, La Saizel and La Hawzel, and gave them as a gift to Demon King Gele. Gele turned the twins into Dark Lords, who pledged their loyalty to the demon king.

Because the two were originally a single entity, the pain and emotions one feels are shared by the other. It is entirely possible for them to merge again into La Vaswald, which would result in the obvious death of the Dark Lord sisters.