Sebastian is the brother of Alonso, the King of Naples.
He helped Antonio usurp Prospero, and is now convinced by the latter to kill his own brother and thus become King, the rightful heirs being either drowned or in Tunis. Prevented by Ariel’s actions from murdering Alonso, he follows him in his search for the missing Ferdinand. He is arrogant and insulting to his lesser. Ariel’s imprecations leave him searching for someone to fight. He is frightened at the magician’s knowledge of his plot against his brother, but recovers enough to mock Stefano’s pretensions.