Prospero- Prospero's character appears to be metaphor for Shakespeare himself in that through his writing he can manipulate his characters just like Prospero manipulates everyone in the play. 

Ariel- The servant, spirit-like character appears to represent the magic of the stage and that anything is possible in the theatre.  Prospero, or the author, uses the magic of Ariel only during the play and in the end gives it up, showing that the magic is only possible in the theatre. 

The Tempest- the storm represents the twists and turns of one's life, and how quickly things can change because of one event.  The storm brought justice to Prospero, and love to Miranda, along with affecting all of the characters in this play.