Xavier was born in Morocco in 1160. In 1192, as a Moorish warrior fighting in the Third Crusade, Xavier was killed in battle. Having awakened as an Immortal, he was found by Immortal crusader Henri St. Cloud who taught him everything about his Immortality. Xavier repaid Henri by taking both the name St. Cloud and his mentor's head. Xavier would become a great fighter and powerful Immortal, but also became an assassin, a thief, and murderer. Xavier was a hedonist who would do anything to become rich, including killing to make a profit. According to Xavier, mortals were beneath consideration and so killing them meant nothing to him.

Xavier has been observed using various swords over his life and in his battles. His first sword was a scimitar, followed by a Japanese Military Katana which had been his sword for seventy years. After his hand was lost, he used Anton Legris’ one handed Charles V sword. He also used his prosthetic arm as a shield in his sword play.