Prince William, also known as Will, is the fiancé of Princess Monica.
William is shown to be quite careless and dim-minded throughout the series. Though his heart resides in the same place—to protect. William can be dull, as he always thinks about playing the role of hero and nothing else. However, despite that, he is shown to have characteristics of jocularity and justness. Prior to his impulsive state, William is reckless, though he is shown to be highly observant and deeply secretive under his joyous attitude.
The twins first see him in episode 3 where Aunt Hilde gave the two the job to take him to the prison. It is unknown how he was kidnapped. Dani and Dorian then proceed to take him in a cage suspended with brooms. Dorian not be able to ride a broom to save his life(but ironic to save Monica's not Williams) gets kicked down but Dani in the cage along with William. In this humorous situation William stares and Dorian whines to Dani that the "delinquent" is staring at him funny.
He grabs at Dorian in hope that he would listen and describes the twins as "don't like them" which Dani mistunderstand, later saying "we're just as good as them."
One of the warlocks state that what William is fighting for is in vain since it's against the Wytte family(this is how we see how much power the Wyette family actually has). William replies that it is not in vain as he dramatically poses along with the other princes as if it were "bringing out the bestselling album of 2015"(Top Commenter: Rima Dagdag). This is when the reader starts gets a glimpse that the twins may be on the wrong side.
"You might think everything is in vain... but we're gonna keep fighting!" -in Episode 4