Prospero

Prospero was a character in William Shakespeare's play The Tempest.

He was the rightful Duke of Milan, being brother to Antonio, who usurped him and exiled him to an island. Prospero was also the father of Miranda, who eventually fell in love with Ferdinand. (PROSE: The Tempest – A Work in Progress)

First thoughts
In his earliest working notes for the play, Shakespeare pondered over it being a boy/girl love story featuring feuding fathers who were Kings or Dukes of somewhere in Italy, possibly Milan or Naples. Later, having decided the feuding fathers would be both Dukes of Milan, he outlined an altered version in which one had deposed the other and exiled the deposed Duke to an island, where he remained until the usurper Duke was shipwrecked there, at which point the deposed Duke murdered the usurper. Shakespeare thought of this iteration as a revenge tragedy but quickly discarded it upon reminding himself the brief was for a romantic comedy. Consequently, he revised the plot again by framing the deposed Duke as the "good guy" and making him forgive the usurper rather than kill him, after which "everybody goes home". Shakespeare questioned why the usurper exiled the deposed Duke instead of killing him when he had the chance and made a note to think up a good reason for this potential plot hole. He subsequently decided that the Dukes could be brothers, adding in the family angle as well as explaining why they would not be eager to kill each other.

In his notes on more specific details, Shakespeare wrote that the usurper Duke could try to kill his ally the King of Naples only to be stopped by the deposed Duke in what the playwright himself described as "nice irony". He also considered the possibility of the shipwrecked ship being undamaged to allow everyone to go home at the end but deemed this a "bit implausible", highlighting in addition to this the already-quite-large coincidence that the usurper Duke ended up on the same island as the deposed Duke, though he also acknowledged that he "got away with it" in both The Comedy of Errors and Twelfth Night. Soon after this Shakespeare selected a "rich-sounding name" for the deposed Duke on account of his former wealth, settling on Prospero after rejecting Wealthio and Magnifico. (PROSE: The Tempest – A Work in Progress)

Following Forbidden Planet
At some point, the Tenth Doctor became aware Shakespeare was struggling to write his play. He sent him a battery-powered Blu-ray player and a copy of Forbidden Planet to draw inspiration from, reasoning that it was "not stealing" because the film was based upon the version of The Tempest Shakespeare was about to write.

Imbued with new thoughts, Shakespeare decided that Prospero was not just a Duke but also a wizard who studied books of magic, though he was still uncertain as to whether Prospero had taken them with him to the island or developed magic powers whilst there or both. Using a magic staff, Prospero caused a storm at the play's beginning which brought the usurper Duke to the island, negating the nagging coincidence of the two Dukes ending up in the same place. Shakespeare also expressed a desire for Prospero to have a "metal man to carry out orders", briefly thinking of a robot as in the film, before changing this to a fairy or familiar spirit (which he named Ariel) as he was not keen on the resemblance there would be to a suit of armour, thinking the audience would "never buy it". To explain Ariel's debt of gratitude towards Prospero, Shakespeare later settled on him being the one to free Ariel from the magic tree where he had been trapped following the death of the witch Sycorax, who was responsible for his creation.

Altering the love story aspect of the play, Shakespeare determined that the girl was Prospero's daughter and was exiled to the island with him. Prospero then used Ariel to put the boy "through the mill a bit" to check that he was truly worthy of his daughter. Shakespeare also utlised Ariel to help Prospero sort out the court intrigue and save the King of Naples' life. In the masque section, Prospero summoned up an invisible band.

Coming to the play's conclusion, Shakespeare outlined that Prospero would set Ariel free as well as give up his magic staff and books. He also briefly detailed a "big show-down" between Prospero and Sycorax featuring "duelling magic staffs, lots of explosions, smoke [and] trapdoor business". Summarising that the three plot lines (the court intrigue, the love story and the comedy business with the clowns and Canibal) would all be "sorted out" by Prospero and Ariel, Shakespeare wavered over whether this was "too easy" and if he could claim it was a deliberate Deus ex machina to impress Johnson, pondering if there was a potential gag in Dukes ex machina. Brushing aside these concerns, he stated in his notes his belief that he was "nearly there" and that the rest of the story would "write itself". (PROSE: The Tempest – A Work in Progress)