Prospero is the rightful Duke of Milan, though his kingdom and title were usurped by his brother Antonio. Prospero was able to survive a plot on his life, and he and his daughter Miranda were set aboard a wrecked craft, but managed to land safely on the island. Prospero is able to gain control of the spirits of the island, and uses his vast knowledge and control over the spirits to direct acts of magic as he pleases. He is ruler of the island, after taking control of it from its rightful heir, Caliban, and he makes sure that Alonso's ship wrecks on the island, so he can get his revenge on his brothers for their wrongdoing.