Sir William was once a heroic paladin and member of the Seven Heroes, who was powerful enough to contribute to the original defeat of the Old Overlord.
Yet over time he became corrupted, summoning a Succubus Queen in order to satisfy his own dark desires with the help of his cult the Red Dawn. As a result of this evil union his people were becoming corrupted by the Heaven's Peak plague - transforming them into undead zombies. Sir William was also to be wed to Lady Velvet but had his wedding ceremony interrupted by the revived Overlord, Sir William taunted his old foe and engaged him in battle. During this battle, Sir William spoke of his contempt for his former life of heroism and his new philosophy of liberation via tossing aside morality. After a brief confrontation Sir William proceeded to lead the Overlord in a chase across the palace, unleashing succubi and henchmen along the way, he also reveals that he has learnt powers from the Wizard and utilizes them in battle. In the end however Sir William's magic and trickery are no match for the Overlord and the corrupted paladin is slain.
- Like all of the Seven Heroes, Sir William represents one of the seven deadly sins, in this case lust.
- The seven heroes are also a parody of a typical fantasy-rpg-team, with William being the paladin.