the island from him. He thinks the island is his birthright because his mother was there first.

According to Caliban, Prospero tricked him by treating him kindly in the beginning so that he would show Prospero the secrets of the island.

This island's mine, by Sycorax my mother,Which thou takest from me. When thou camest first,Thou strokedst me and madest much of me, wouldst give meWater with berries in't, and teach me howTo name the bigger light, and how the less,That burn by day and night: and then I loved theeAnd show'd thee all the qualities o' the isle … (Act 1, Scene 2)

It is Prospero’s contention that Caliban tried to assault Miranda, and therefore their treatment of him is justified.  Caliban doesn’t deny it, using the accusation to tease Prospero and Miranda. They both hate Caliban, and Prospero continuously threatens him.

When Caliban meets Trinculo and Stephano, he tries to convince them to kill Prospero and take the island from him.

RememberFirst to possess his books; for without themHe's but a sot, as I am, nor hath notOne spirit to command: they all do hate himAs rootedly as I. (Act 3, Scene 2)

Caliban claims that everyone on the island hates Prospero and he has enslaved all of its magical creatures and inhabitants. Prospero definitely seems to use Ariel to do his bidding. Although Caliban says that once they take Prospero’s books from him he will be helpless, Prospero is playing a much better game. Caliban doesn't have a chance against him.

However, at the end of the play, Prospero decides to let go of all of his grievances. He could have punished Caliban and his confederates for their attempted attack on him, but he chooses not to. He lets go of his magic and leaves the island to Caliban.

Caliban hates Prospero and Miranda because they have made him their slave. As he states in act 1, scene 2,

I am all the subjects that you have,Which was first mine own king. And here you sty meIn this hard rock, whiles you do keep from meThe rest o’ the island.

Caliban says that he was first his own "king"—that he owned the island and had freedom and autonomy. Now he is held prisoner and forced to do Prospero's bidding.

As postcolonial critics have long pointed out, Caliban's situation illustrates in a microcosm the plight of Indigenous peoples around the globe: European colonization upended lives and cultures. Like many people in other places, Caliban welcomed the European newcomers with open arms and taught them what they needed to know to survive on the island. Having the knowledge he needed to survive, Prospero then turned on Caliban and made him his slave, justifying this by characterizing him as a lesser being, a monster whose lower instincts had to be controlled.

Looked at from Caliban's perspective, Caliban has every right to feel angry. He believes that Prospero deceived him with false friendship while secretly despising him and using him. Once Prospero got the upper hand, his true colors emerged, and he treated Caliban cruelly.

Caliban is wrong that he is the only subject Prospero has, although he is right that he is the only human subject. Prospero also "owns" the spirit Ariel, whom he saved from a spell cast on him by Caliban's mother, who kept Ariel imprisoned in a cloven (spilt) pine. Ariel serves Prospero and represents the "good" slave, but he, too, longs for freedom. This shows that Caliban is not wrong or perverse, as Prospero and Miranda characterize him, in chafing at his slavery. Shakespeare understands enslavement as a fundamentally negative situation.

Caliban hates the way he is treated by Prospero because, as he says himself, "This island's mine, by Sycorax my mother, / Which thou takest from me." In this sense, Prospero is like a European colonizer, who lands in a foreign country and enslaves the indigenous people he finds there. Caliban also claims that Propero only ever treated him nicely when he first arrived so that Caliban would show him "all the qualities o' the isle." After Prospero had got all that he wanted from Caliban, he imprisoned him "in this hard rock" and treated him as a slave.

Prospero also tortures Caliban. He uses his magic to inflict Caliban with "old cramps" and "aches." Caliban describes the tortures as "like apes that mow and chatter at me, / And after bite me." He says that "sometime am I / All wound with adders who with cloven tongues / Do hiss me into madness." Thus, Caliban hates Prospero for two reasons. The first is that Prospero took from him the island which was rightly his. And the second is that Prospero has enslaved him and continues to torture him.

Prospero, in his defense, claims that he only ever started treating Caliban badly after Caliban tried to "violate / The honour of my child." In other words, Prospero treated Caliban kindly until Caliban tried to rape his daughter.

Caliban deeply resents being treated like a slave by Prospero. Yes, the exiled Duke of Milan did Caliban a huge favor by saving him from his evil witch mother, Sycorax. But Caliban doesn't think that gave him the right to take over "his" island and turn him into a glorified lackey. Although, to be fair to Prospero, he only started treating Caliban badly when Caliban attempted to rape Prospero's daughter, Miranda, so he has perfectly valid reasons for keeping this revolting brute under control.

Nevertheless, Caliban seethes with resentment at being under Prospero's thumb. In fact, he's so bitter at what he perceives as his unfair treatment that he actually tries to convince Trinculo and Stephano to kill Prospero. Caliban daren't do it himself; he's too scared of Prospero to even think of trying. But it's a measure of how hard he thinks he's been done by that he should want to see his lord and master dead.