Prospero has two servants in The Tempest. One is Ariel, a sprite who Prospero rescued from a tree (where Ariel was sent as punishment by the witch Sycorax). As a result, Ariel feels grateful towards Prospero and does his bidding. However, Ariel is eager to win his freedom, and he tells Prospero in Act I, scene 2:
"Remember I have done thee worthy service;/ Told thee no lies, made thee no mistakings, served/ Without or grudge or grumblings: thou didst promise/ To bate me a full year."
Ariel has served Prospero honorably and dutifully, and Prospero promises to free Ariel in return, which he does at the end of the play.
Caliban is also Prospero's servant, though he is more like a slave than a servant. Caliban lived on the island with his mother, Sycorax, when Prospero arrived on the island. At first, Prospero was tender towards Caliban, and Caliban fell for Prospero's tenderness and was coaxed into his current state of servitude. Caliban says to Prospero: "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." Caliban resents the gratitude and love he showed towards the man who now keeps him in bondage. Caliban, who is described as dark and earthy, is in many ways the opposite of the spritely and kind Ariel, and many critics have seen Caliban's servitude as symbolic of the oppression of darker-skinned peoples by white colonialists.