Little is known about his life, but as revealed in Rise of the Titans, he shared his father's belief and pursuit of transcending organic life and extending their lifespans by becoming one with machines. After his father secretly underwent the process of uploading his consciousness onto an artificial platform, Montgomery chose to undergo the same process and dedicated the rest of his existence to guarding the platform intended for his father (since Galen uploaded his consciousness onto a different platform that now remains lost). After the process, Montgomery decided to begin calling himself MONT-E.
He continued to guard his father's tomb until the present day when the House of Mythos visited it. Though MONT-E was friendly and helpful to Azure the Dragon, when Garnett the Phoenix appeared and damaged Galen's platform, MONT-E became distressed and expelled the Mythos family from Galen's tomb before proceeding to repair the platform.
As a result of converting himself entirely into a machine, MONT-E has virtually no sense of time and is extremely patient. Though as seen with Anubis the Jackal in which excessive cybernetics can result in the loss of magic, it appears that by transcending organic life and becoming one with technology has allowed him to reclaim his technomancy. In the brief moment of his appearance, it became clear that MONT-E is a well-thought out individual and plans for nearly any outcome, even having a number of backup platforms for himself should he suffer damages. Additionally, the tragic obsession with guarding his father seems to be the only thing that keeps him going. However, it is uncertain whether MONT-E will ever truly reunite with his father.