The tempest

I think Prospero is rather angry at his brother Antonio. Antonio usurped the dukedom of Milan from his Prospero, while Prospero was absorbed in study. Antonio is probably the least scrupulous character in the play, and he is the originator of another plot to take the throne from Alonso through more murders‹though this plot is engineered by Prospero, and made possible by Ariel's magical powers. He is typically sarcastic and remote, and unrepentant of his crimes. Prospero seems to soften his revenge by the end of the play.