Ácolitus is the chiefest entity in Esha, for he is the fabric of existence and harbinger of creation. From his ambition and mistakes came the Eshan, and from the mortality. He is beyond categorization elsewhere.
Zarthum ranks alongside his creator, being equivalent in status to the Eshan but the sole conscious, sentient creation of Ácolitus. Unlike the Eshan, whose objective was to create according to their desires, Zarthum was meant to destroy. He was unleashed on the turning of the Imperial and Wandering eras, slaughtering mortals and Eshan alike, until Corgastor came forth from the Void. They fought, annihilating Zarthum and killing Corgastor through the Eshanic Mandate which he violated to save his kin. Ruination averted.