I’d like to believe that this king is a fallen Archangel. After all, in Christianity, the lord of hell, Lucifer was said to be a fallen Angel.
Lucifimos, The Fallen.
They were the first Archangel that Mother created, and originally took the role of an overseer of life on the countless worlds across the universe. However, soon they became jealous of Life and Mother’s favoritism towards it. They felt that life was merely a lesser expression of Angels which served no purpose. In his eyes, Life is only a parasite on the Celestial Plane that should be eradicated. They rebelled against heaven, before Mother defeated them. They were punished by being mutated into a demonic reflection of their once banished and angelic form, before they were then banished to the edge of the universe.

Now they command countless other evil beings from across the cosmos in order to claim what they feel is their rightful throne, promising them the infinite energy and bliss the Celestial Plane has.