Caliban is a product of nature, the offspring of the witch Sycorax and the devil. Prospero has made Caliban his servant or, more accurately, his slave. Throughout most of the play, Caliban is insolent and rebellious and is only controlled through the use of magic. Caliban claims the island as his own and maintains that Prospero has tricked him in the past.
Caliban represents the black magic of his mother and initially appears bad, especially when judged by conventional civilized standards. Because Prospero has conquered him, Caliban plots to murder Prospero in revenge. It is clear, though, that Caliban is a poor judge of character: He embraces Stefano as a god and trusts his two drunken conspirators to help him carry out a plot to murder Prospero. In many ways, Caliban is an innocent, reacting to emotional and physical needs without the ability to think through and fully understand the events and people who surround him. He is truly a child of nature, uneducated and reacting to his surroundings in much the same way that an animal does.