Sebastian is the brother of King Alonso of Naples. He is full of villainy like Antonio, the brother of Prospero. He becomes a partner with Antonio in the conspiracy against his own brother. But Sebastian is not so wicked by nature. He is prevailed upon to become wicked. His conscience is very weak. That is why the voice of his conscience is easily silenced.
Sebastian is very cruel. He joins the plot to murder Alonso and Gonzalo. “When Gonzalo tries to console King Alonso in his grief over the supposed loss of his son, Sebastian tries to add fuel to the fire. He has no sympathy for his brother. He sharpens Alonso‘s grief by blaming him for the whole misfortune and the shipwreck. He scolds Alonso and tells him that he should not have married Claribel, his daughter, against her wishes.
Like Antonio, Sebastian is also a mocker. As a matter of fact, Sebastian and Antonio form a good pair to conspire and to make fun of others. Sebastian’s mockery is a cover for his evil nature. In the words of Gonzalo, Sebastian is a man who would like to taugh at nothing. Sebastian also makes fun of the strange shapes which bring in the feast. When Ariel tries to threaten the three sinners, Sebastian tells them that he can light with anyone.
There is no feeling of remorse in Sebastian, He is without any principles and morality. There is no inherent evil in him. But once he is influenced to take to the evil path, there is nothing to stop him. He is a hateful person.
He is a bold but careful conspirator, When Antonio speaks to him about the plan to kill Alonso, he is simply amazed. He thinks of the merits and demerits of the suggestion. He thinks that Alonso’s daughter could become the next heir to the throne. Finally he is persuaded by Antonio to join the conspiracy. Once he has agreed to become a partner in the conspiracy, he decides to give it a practical shape.