Caliban enters, carrying wood. He delivers a monologue in which he curses Prospero and describes the many torments Prospero's spirits inflict on him. Just then, Trinculo, Alonso's jester, enters. Caliban mistakes him for one of Prospero's spirits here to punish him for doing his chores slowly. He lies down and hides under his cloak.
Caliban describes in vivid language the various torments Prospero uses to subdue and punish him. These examples supply motivation for the murder plot Caliban will devise in the next act.
Trinculo, hearing thunder, fears another storm coming and looks for a place to hide. On the ground, he spots a brownish lump with legs (Caliban partially hidden by the cloak) and thinks it is a "strange fish" (2.2.25) that he could perhaps bring back to civilization and sell as a curiosity. Upon further scrutiny, he believes that it is an islander that hat been struck by a lightning bolt. Crawling under the cloak for shelter, he remarks, "Misery acquaints a man with strange bedfellows" (2.2.35).
Trinculo is a comic character, and his speech is ridiculous. His instinct to capture and sell the "strange fish" reflects the desire common among Europeans in Shakespeare's time to exploit the "exotic" plants, animals, and people living in lands visited by European explorers and colonized by European nations.
Stephano, the Alonso's butler, enters, drinking and singing very badly. Whether because of Stephano's singing or because Trinculo has crawled under his cloak, Caliban cries out, "Do not torment me! O!" (2.2.51). Stephano hears the noise and notices a brown mass with a pair of legs sticking out on each end. He thinks it must be a two-headed, four-legged monster of some sort. He, too, considers capturing and selling this creature as a curiosity back home. He gives one head (Caliban's) a drink, hoping to tame the monster. Trinculo, meanwhile, recognizes Stephano's voice and calls out to him. Stephano pulls him out by the legs. The two embrace and share their stories about surviving the shipwreck.
Like Trinculo, Stephano is interested in capitalizing financially on the Europeans' interest in the exotic. Just as American colonists used alcohol to win over and subdue native peoples, Stephano supplies Caliban with alcohol to "tame" him.
Caliban, meanwhile, has never had wine before and gets immediately drunk. He thinks that the owners of such a marvelous liquid must be gods. Kneeling in worship, Caliban declares himself Stephano's subject. Stephano enjoys the admiration of the "monster" (as Trinculo repeatedly calls Caliban) and relishes the drunken Caliban's offer to kiss his feet.
Caliban's mistaken belief that Stephano is a god echoes similar mistakes made by natives upon the arrival of Europeans. Notice also how quickly Stephano takes to the idea of becoming a master rather than a servant.
Caliban volunteers to show them around the island and expresses a hope that Stephano might be able to deliver him from servitude to Prospero. Stephano, meanwhile, fantasizes about becoming ruler of what he believes is a deserted island, while Trinculo comments, in a series of asides, on the absurdity of the scene: "A most ridiculous monster, to make a wonder of a poor drunkard" (2.2.142–143).
Caliban attempts to escape slavery by enslaving himself to someone else. Trinculo rightly ridicules Caliban, but notice how Caliban's tactic is exactly the same as the one used by Antonio, who gave his allegiance to Alonso in order to overthrow Prospero.