Maurice was the original bearer of a unique Crest with his name. It is said that he was among the original elites who assisted in defeating Nemesis. He was, alongside Seiros and the Ten Elites, celebrated across Fódlan as a result. Some time after that, he overtaxed his crest and Hero's Relic, Blutgang, causing him to transform into a Black Beast. Taking residence in a forest and losing control of his body, his beast form began gruesomely killing any individual foolish enough to enter his territory. For this, he was expunged from history and forsaken, and an attempt was made to have his bloodline terminated. Contrary to common belief, Maurice would still have descendants of his own, but all inheritors of his crest were believed to be cursed, thus his Crest was renamed "the Crest of the Beast." Rumors began to circulate that any descendant of Maurice would transform into "The Beast" that stalks the forest.
Even after 1000 years, his involuntary attacks did not stop. The attacks lead a Crest scholar with some knowledge of the Crest of the Beast to falsely accuse Marianne of being The Beast herself. Thanks to Byleth and her classmates' assistance, Marianne confronts Maurice and is able to quell his beast form, retrieving Blutgang from his corpse and ending his suffering. Marianne notes that all that remained of Maurice was the sword and human bones.
Maurice derives from the Roman name Mauritius, meaning "dark, moorish."