Board Thread:General Discussion/@comment-29853277-20170719023533/@comment-29853277-20170909105348

Just so you don't need to check out the page again, here's the justification.
 * Absolute Ego - Mattias' Ego was sealed by the magic he used to protect himself from his Realm's destruction, by sealing off his Ego from any and all outside force. Essentially, it acts as a vastly superior form of Divine Armour, one that cannot be pierced even by the Apeiron of the Gods, preventing them from changing his being in any significant way, shape or form. He cannot die. He cannot be erased. He cannot even be harmed but for the smallest of scratches. His body, his concepts, his causality, his mind, his soul, the fundamental nature of his being ... all such things are sealed, and cannot be altered except in the smallest of ways. However, due to the panicked emergency nature of the sealing, it is flawed. Not only does it not allow for exterior forces to affect him, it also prevents him from changing from the inside. His path is set, and he cannot stray from it. His desires, his emotions, his feelings ... all are captured as they were at the moment of the sealing, when his Realm was destroyed. Consequently, he constantly feels the same feelings of terror, despair, rage, and desire for vengeance that he felt then, never waning in their intensity. He is not completely unchangeable, and small, cumulative, alterations can be made to his psyche over the course of countless eons, to allow him new desires and emotions, but those feelings of rage, pain, loss and despair will always be lurking just below the surface.