Ariel is an air spirit in Shakespeare's The Tempest. For much of the play, the audience sees him doing Prospero's bidding: creating the storm by which Alonso's boat is cast ashore, tormenting Caliban, and chastising Alonso, Sebastian, and Antonio. Ariel appears obedient to Prospero as repayment for Prospero's having freed him from imprisonment; before Prospero arrived on the island, a witch named Sycorax had trapped Ariel in a tree. However, Ariel cannot be seen as a blindly obedient character because he challenges Prospero regarding his duties. Prospero has promised to free Ariel, and Ariel reminds him of this promise. Ariel is clearly upset when Prospero tells him that he must do yet one more act of magic. So although he is willing to perform his tasks, Ariel desires to be free. Throughout his interactions with the other characters, Ariel remains neutral and does not appear to have any feelings one way or the other about the acts of magic that he performs upon the characters.