"Scion of darkness ruling and protecting those who live in the underworld, in opposition of Lahabrea, Abyssal Celebrant and scion of light. In the course of his rule, he submitted to avarice, and the darkness took his heart, transforming him until he was both evil and corrupt. Then in his cowardice he bind a Goddess of the Demsne of Ice, and using her as a living shield, he challenged the gods. Defeated before their might, he fell screaming into the depths of hell , there to be imprisoned for eternity."

The part where it mentions a binding to a Goddess makes me believe that the image you see is the Goddess and not Mateus himself.

But who knows.