Stephano is Alonso’s butler. He has something of a taste for liquor, and is well-served when he is cast up on the shore with a butt of wine that he held onto to avoid drowning.
Finding Trinculo with Caliban, he swiftly gets the latter drunk and makes him swear obedience to him. He quickly becomes lord-like, threatening Trinculo with violence. He listens to Caliban and decides to kill Prospero so as to become king of the island and marry Miranda. He is quickly distracted from this plot by some shiny new clothes, then tormented by invisible spirits, before discovering that his master is still alive and that he is in serious trouble.