Mordex is the Drama Family's pet dog. More specifically, Ember's. Despite his exceptional combative skills, he has been treated harshly by her, subject to animal abuse. Ember had laced explosives in his chew toys in the intent of harming him. She would also give him beatings, which would eventually lead to his death.

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In his undead form, Mordex would get back at Ember for her mistreatment of him. Once that led to her first death and the second which led to his own banishment. During his time in the Afterlife, he had encountered Nix, who would start a fight. In the midst of their fight, they had conversed to each other about their common distaste for the Drama Family. Despite their similarities, Nix continued her attacks until Mordex was defeated.