Zlo is a powerful demon lord who commanded a vast portion of Hell. His power actually has the disadvantage of ageing his physical form and so has managed to gain the ability to use the forms of his demon servants upon disintegration and the willing slaves allow themselves to be consumed by him, and the cycle continues. Bored of his existence as being in need of others and maybe being seen as not strong enough to be independent escaped through a Hellmouth in an unknown point in time and the ordeal kills him. However, he takes the form of a human and remains immortal from then on, establishing a cult that follows his will that manages to stretch out all over the world.