Originally a trusted friend and advisor from the peaceful kingdom of prince Maximo, Achille became powermad and usurped the kingdom with his new dark powers while Maximo was out venturing prior to the events of the game. With his unexplained dark power, he made Sophia his queen and used a giant drill to release human souls out of the Underworld to increase his power and fashion his own undead army out of them. When Maximo returned to see what was happening to his kingdom, Achille killed him, but he is revived by Grim so the two can stop Achille, starting by finding the sorceresses council to aid them.
After finding three of the four sorceresses, Achille kills sorceress Sephonie to hinder Maximo, but he revives her with Grim's help. Maximo fights against Achille Atop the Great Drill, where he uses all his magic powers against Maximo, including using a barrier, creating a giant energy head, and transforming into a giant monster. After taking enough hits, his magic will stop working and he will fight with his scepter, which has a hidden blade, and is killed by Maximo. After his death, it is revealed that a demon was controlling Achille to gather power for itself.