Alonso is one of three villains of the play. The other two villains are Sebastian and Antonio. But he is not so wicked as the other two. Even then he is guilty of a serious crime, Ariel considers him one of the three men of sin, most unfit to live.
Alonso is the King of Naples. He did not have good terms with Prospcro who was the duke of Milan. When an opportunity came, he gave full support to Antonio to throw out his brother Prospero from his dukedom. He satisfied his feeling of enmity and he also started receiving an annual ransom from Antonio. Alonso behaved in a very heartless and fcclingless way by throwing Prospero and his baby daughter, Miranda at the mercy of bad weather in a rough sea.
Alonso is a victim of a ship-wreck; He had gone to Tunis to marry his daughter. This marriage took place against the wishes of his daughter. On the way back, the ship carrying the King and his party was caught in a tempest. The party was scattered into several groups, and washed ashore. Alonso loses his son Ferdinand in this ship-wreck. He feels distressed over the supposed death of his son. He deeply repents for forcing his daughter to marry against her will.
He is an affectionate father. He loves his son very much. When he thinks his son to have been dimmed, he feels grief-stricken and heart-broken. He wanders about the island in search of his son. He is almost mad with worries. When he sees his son alive, his joy knows no bounds.
He is a man with a conscience. If at all he joined the conspiracy of Antonio to throw out Prospero it was merely a political game. He was not so wicked as Antonio. He looks like a noblehearted soul who repents of his evil deeds. When he meets Prospero in the last act, he begs to be excused. When he sees Prospero standing before him, all his feelings disappear. He has a conscience which is absent in Antonio. He wanted even to ask pardon of Miranda but Prospero forbids him to do so. Such a thing in the eyes of Prospero would not have looked nice.