The Grand Duke's most striking quality is that he is extremely clumsy and usually calm, a direct foil to the King's romanticism and passionate temper. He is also rather nervous - likely due to the King's temper being taken out on him so frequently - but not depicted as cowardly. He feels that love at first sight is just a romantic fairy-tale, and points out to the King that the glass slipper which Prince Charming finds could fit any number of girls. He is extremely loyal to the King, despite showing fear of his threats when things go wrong.
The Grand Duke is the 3rd most powerful person in the kingdom after the King and Prince Charming, as he has authority over the guards and palace servants, at the King's orders competently and perfectly arranging the ball to welcome Prince Charming home and find him a wife.
The Grand Duke is first shown with the King, who misses the sound of children running around the castle, and wants to see grandchildren before he passes away. He tries to figure out how to find his son, Prince Charming, a wife. He comes up with the idea of throwing a ball at his castle and orders the Grand Duke to arrange the ball to celebrate the Prince's return home and to find him a wife.
The Grand Duke finds the King's ideas of love at first sight charming but unrealistic, and when he sees Prince Charming finding himself only bored by the women attending the ball, chastises the King gently, telling the king that his romantic ideas of the Prince suddenly seeing a strange girl and falling in love with her at first sight were a story seen only in fairy-tales (made especially ironic by the fact that the story of Cinderella is itself a fairy-tale). But even as he does so, Prince Charming sees Cinderella and is fascinated by her appearance.
The King then orders the Grand Duke to ensure that Cinderella and Prince Charming have a perfect evening, undisturbed, which the Grand Duke competently arranges by closing the curtains to let the two have a private time together. However, when the clock strikes midnight, Cinderella rushes off and the Grand Duke orders guards to try to stop her. He is unsuccessful, but is able to collect the glass slipper she has left behind. When he explains to the King that the girl with whom Prince Charming has spent the evening has disappeared, the King becomes enraged and attacks him for being in league with the Prince and plotting everything. The Duke explains that the girl has left behind the slipper, and the Prince will not rest until she is found, as he is determined to marry the girl who fits the slipper, finally satiating the King's rage. The Duke then points out sensibly to the King that the slipper may fit any number of girls' feet, but the King simply points out that that is the Prince's problem. He then orders the Duke to find the girl who fits the slipper.
The next morning, after a long night of searching, he finally arrives at the home of Lady Tremaine. After trying the slipper on Anastasia and Drizella (who both do the hardest way to get it on), he is about to leave, but then Cinderella appears. Despite Lady Tremaine's insistence that Cinderella is only a serving girl and could not possibly have been at the ball (though she is sure that she did), the Grand Duke orders Tremaine to step aside so that he can try the slipper on Cinderella. He calls to his footman to deliver the slipper, but Lady Tremaine trips him, causing the slipper to fly and shatter into pieces in front of the Duke and Cinderella. This makes the Duke feel horrified and terrified about the King's reaction. Cinderella, however, reveals that she has the broken slipper's match, and the Grand Duke is overjoyed to the point he kisses the slipper. For even if the king finds out he has undeniable prove that Cinderella is/was the girl at the ball. He slides the slipper onto her foot, and finds that it fits. He then takes Cinderella, along with her mice friends, Bruno and Major, to the castle, where Cinderella reunites with Prince Charming.
Finally, the Grand Duke appears at the film's finale, where he and the King jubilantly throw confetti to celebrate the wedding of Cinderella and Prince Charming, who both walk down the stairs and ride off in a carriage that takes the newlyweds on their honeymoon.
Cinderella II: Dreams Come TrueEdit
In the sequel, the Grand Duke reappears as the King's right hand man and assistant. The Duke helps Cinderella adapt to her new princess life which proves to be difficult. In the first story "Aim to Please" Cinderella must gain the ability to both act and dress as a princess as well as set up the royal ball. The Duke originally offered to help Cinderella but the job was instead given to his rival Prudence. In the end Cinderella throws an excellent ball while the Duke develops a romantic relationship with Prudence. In the next story, he and Cinderella have grown a close friendship and spend most of the current days working around the castle alongside it's staff. In the end of the segment the Duke and the King attend the Spring Festival, which culminates in both of them taking a ride on a mad elephant.
Cinderella III: A Twist in TimeEdit
In the third film, the Grand Duke reappears as a main character once again. Lady Tremaine has stolen the magical wand of the Fairy Godmother and change history so that Anastasia was the one who fit the slipper. The Grand Duke maintains his nervous personality and seems to have more of a friendship with Prince Charming in this film.
He first appears reliving his role from the first film after Lady Tremaine reversed time and fits the shoe on Anastasia. Unlike the villains of the film The Duke is oblivious to the time switch and has no knowledge he is reliving the shoe fitting. He gives Lady Tremaine a tour of the castle and believes Anastasia will not make a decent wife. The Duke attends the wedding where Cinderella is revealed to be the true princess and peace is restored.
In Kingdom HeartsEdit
Kingdom Hearts: Birth by SleepEdit
Like in the film, the Grand Duke appears watching the ball as it took place, gladly seeing that the Prince had found a maiden (Cinderella) he seemed rather fond of. However, Terra, who had escorted Cinderella safely through Unversed-infested halls, noticed that there were more Unversed above the Ballroom and asked the Grand Duke for directions to reach the Balcony. To make matters worse, the Unversed fed off the jealousy of Lady Tremaine and her daughters and transformed into the Symphony Master. Terra managed to slay it and asked the Grand Duke how long Unversed had been infesting the Castle of Dreams. The Grand Duke informed him that a boy in a mask visited the kingdom a little while ago and released the creatures, which obeyed him without question.
However, things toke a turn for the worse as at the stroke of midnight, the beautiful girl fled the castle, leaving behind a single glass slipper. It was then that the King gave the order to hold a search party, saying that any maiden who fit the slipper would be Prince Charming's bride. The Grand Duke then left without hesitation to carry out his command.
Eventually coming before the young Aqua, a Keybearer from outside the Castle of Dreams and informed her of Lady Tremaine's identity after Aqua received a bad vibe from her. He then traveled to Tremaine's home to begin his search. Luckily, CInderella escaped from her room after being imprisoned by Lady Tremaine and he fitted the slipper on her foot. However, an Unversed created from Tremaine's jealousy tried to kill them. Luckily, Aqua slew it and its progenitor, allowing the Grand Duke to take Cinderella to the Prince.
On Sora's TeamEdit
The Grand Duke is one of the members who stays in his world to call Sora's team whenever enemies attack the kingdom and monsters show up.