The Tempest has a large cast of antagonists, all of whom pose challenges for the play’s protagonist, Prospero. The most important antagonists are Alonso and Antonio, who conspired to assassinate Prospero when he was Duke of Milan, and who are responsible for his exile on the island. Although Alonso wronged Prospero in the past, his actions during the play are not particularly antagonizing. Instead, he spends most of the play mourning the death of his son. Antonio’s case proves a bit more complicated, since in Act II he conspires with Sebastian to assassinate Alonso, echoing his betrayal of Prospero twelve years prior. Prospero confronts both men in Act V, and Alonso immediately confesses his guilt and expresses his shame. Antonio, by contrast, doesn’t have any lines in the final act. Prospero ultimately forgives Antonio, and closes the matter by demanding his dukedom back.
The Tempest also features an array of lesser antagonists. Caliban sees Prospero as a violent imperialist who unjustly took control of the island, which had previously belonged to him and his mother, Sycorax. Caliban acts most insubordinate when he befriends two lesser antagonists, the drunkards Stephano and Trinculo, with whom he plots the murder and overthrow of Prospero. Of course, Caliban and his associates don’t stand a chance against Prospero’s magic, and their plot fails spectacularly. At the end of the play, Caliban remains fundamentally unchanged as a character—still as hateful toward Prospero as ever. Compared to Caliban, Prospero’s other servant, Ariel, seems like an angel. Yet Ariel also incites Prospero’s wrath when he reminds his master of his promise to free Ariel after a year of faithful service. Although Ariel’s character doesn’t change much in the play, he does gain his freedom in the end.