Answer:
He promises Ariel his freedom but at the end doesn't free him
Step-by-step explanation:
Prospero is one of the protagonists of the play The Tempest by William Shakespeare. He is the true Duke of Milan who was usurped by his brother Antonio and was left at sea to die along with his young daughter Miranda.
In the play, Prospero has mastered some forms of dark magic with which he uses to hold powerful spirits like Laban and Ariel captive who do his bidding. Prospero promises to free Ariel after his last assignment but he fails to do that which shows quite clearly that he is manipulative.