Duke is the familliar of Chocola Meilleure. He is a frog who used to be a wizard. His real name is Poivre, which translates to 'pepper' in french. He is actually Chocola's uncle.
Duke is a red and black striped frog. He has deep green eyes. He is very long and his fingers and toes end with nubs. Blanca thinks he is tacky.
As a human, Poivre has red shaggy hair with a black streak and red eyes.
As both a familiar and in his true form, Poivre/Duke, was shown to be extremely powerful. As a familiar, he was able to easily tear through Pierre's barrier like paper (in both the anime and the manga) and actually knows Pierre's real name. He was able to create a door to the Magical World easily (to help Chocola in her search for Ombre and happened in the anime only), something that cannot be done by a normal witch, let alone a familiar.
In his true form, he was able to transport Chocola, Vanilla, Blanca, and himself from Hollywood back to Japan in an instant. He was also shown to manipulate water in the Le Palais pond to visit Queen Candy. Also, when they were trapped in the Ogre Castle he was able to shield the entire party by himself. (all of these happened in the manga only).
In the manga, he introduced himself as 'Poivre, the water witch, who goes wherever he pleases'. He is the laid-back brother of Cinnamon, Chocola's mother.
When Chocola demands that he tells her about her mother, Poivre is struck at how alike Chocola and Cinnamon were. He reminisces the time when both he and Cinnamon were still young. His father, Corne, was usually frustrated with his wandering attitude, and had wanted him to take over his blacksmith shop. He then states that Cinnamon had walked the straight path, while he was the worthless son, although he never did resent her sister for that.
When he returned to the Magical World after a long period of wandering, he then received the news that Cinnamon was wanted and had been disqualified as a Queen Candidate. He found her in a cave, where Cinnamon was holding Chocola and reveals that Glace is Chocolats father.
He was then prosecuted for helping in hiding Cinnamon. To escape, he used a spell to disguise himself as a familiar, but made a mistake in his spell and accidentally ended up being a real familiar instead. By pure luck or coincidence, he ended up as the familiar of his neice, Chocola, who was chosen as a Queen Candidate.
In the ending, he was shown to have his true form, and attended Vanilla's coronation ceremony with his father.
Duke has a laid-back, go with the flow personality. He tries to help Chocola get hearts, but doesn't really help at all. He is quite lazy and has a vicious rivalry with Blanca. Mostly, he is quite lazy and rude, and has an extensive knowledge about hearts, which proves useful later. Duke is actually Chocolat's uncle, the little brother of Cinnamon, who was transformed into a frog. He tells Queen Candy that he turned himself into a frog to pose as a familiar, as he was wanted by the authorities after he concealed Cinnamon when she was on the run. However, his transformation worked too well, and his magical power as a familiar became too weak to allow him to transform back. At the end of Volume 6 he is returned to his human form via a white heart. At times, however, Duke is quite friendly. He is a bit of a flirt and tries to get together with other frogs. He ends his sentences with "kero."