Antonio is the younger brother of Prospero, the former duke of Milan. He is a villain to the back-bone. A study of his character tells us the ditference between a devil and an angel, His wickedness has a selfish purpose behind it.
Antonio is a treacherous person. He is not at all dependable as a brother. He was trusted by his elder brother, Prospero. Prospero was not worldly-wise. He gave the charge of state affairs in him in good faith and devoted himself to the study of books. This trust was misused by Antonio. He repaid this trust with treachery, deceit and disloyalty. He became very ambitious. With the help of the king of Naples he threw Prospero out of his dukedom. In his lust for power and ambition, he sold his self-respect and state to the King of Naples. He is without the milk of human kindness.
He is a seasoned (much experienced) conspirator. He gets delight by conspiring for personal gains and for the gains of others. On the island the king and Gonzalo and other courtiers go to sleep. He prevails upon Sebastian to kill the king and become the king of Naples himself. He also urges the murder of Gonzalo who might prove a source of danger in the future.
Antonio is a thankless person. Alonso helped him in getting the dukedom of Milan. Now the same Alonso becomes the victim of his plan of murder. By joining the plot against Alonso, he becomes a devil. He his absolutely no conscience. Even a sinful act committed by him fails to produce any remorse in his heart. His skill and resource fulness lie in villainy and not in charity.
He is a heartless person. He joins Sebastian in making fun of Gonzalo when the latter tries to console Alonso in his grief. The king is feeling very sad and disappointed on account of the supposed loss of his son, Ferdinand. He feels no pity for the King’s distressed condition. On the other hand, he tries to further the plot which he himself hatched. When several strange shapes bring in the banquet (feast) Antonio starts mocking. When Ariel condemns the three sinners, Antonio does not feel any feeling of remorse. Even in the end of the play we do not find him repenting of his past sins. That is why we feel no pity for him.