Both of these characters show Prospero's twisted sense of justice. Prospero's use of magic to control Caliban through "pinchings" and chains is somewhat more justified, given the story of Caliban's attempted rape of Miranda. It also clearly shows, however, that Prospero assumes control of situations without taking others' feelings or rights into account. Caliban grew up on the island and had the full run of it for years before Prospero came to its shores, yet this is not given even a modicum of respect by Prospero's self-centered (and ethnocentric) view. His treatment of Ariel is even worse; this spirit did nothing to harm Prospero, but rather is enslaved by the magician simply because Prospero freed him from the tree where he was imprisoned. This was not an act of illusion done to give Ariel a "renewed faith in goodness," but rather a very corporeal act that traded imprisonment...

Nor was this done primarily for Miranda's benefit, but rather was a way to ensure Prospero's increased and continued dominion over his island and its surrounding waters. In short, Prospero is almost completely self-serving not only during the action of the play, but also in the details of his life that occurred before the action of the play that are referenced in the script.
There is definitely a noticeable change in Prospero by the end of the play -- after seeing his daughter with Ferdinand, he realizes the transience of his power over her and over everything else. It is only through seeing her love for Ferdinand that Prospero manages to accept other people's desires and rights, and in doing so he realizes he must give up his magic in order to be a full part of their lives. Good does not come from his magic, but rather from his relinquishing of…