He was the twin brother of the noble Sir Beade and there was little to separate their appearance, save that Beade wielded a sword, whereas Duke carried a battleaxe. Like his brother, he was a bearded man, with dark hair. He wore a cape.
It was Sir Duke who suggested that Tantalon hold the Crown of Gallantaria after Constain’s murder. His choice turned out to be an inspired one with the ageing sorcerer being a brilliant strategist whose battle plans altered the course of the War of the Four Kingdoms and laid the groundwork for Gallantaria's power.
He was known throughout the land for his kind and merciful nature and this proved his downfall. He was sent east to defend the Witchtooth Line with his troops. He fell prey to the dreaded Gorgon, Medusa, who was posing as a beggar woman. When he stepped down to drop a coin in her cup she revealed her face and turned him to stone. Such was the importance of Sir Duke to the kingdom, that Tantalon specified that one of his Twelve Tasks should be to free Sir Duke. His petrified form stood in the Forbidden Caves until Tantalon’s Heir used the stone antidote kept by Medusa to restore him back to flesh and blood.