[EDIT: It occurs to me that I wrote something of a short story – 750 words, so at the end, I am appending a bit of a synopsis of my points]
Act I of The Tempest has two scenes. The first scene details a raging storm. The storm induces a shipwreck. Scene two brings us to an island where survivors of the wreck will eventually turn up. The island is presently inhabited by Prospero, his daughter, a spirit, and a slave.
Prospero begins by finally explaining to his daughter who he, and by extension she, is. I say finally, because as Miranda says “You have often\ Begun to tell me what I am, but stopped\…\Concluding, ‘Stay: not yet.'” (1.2.32-6). Prospero and his daughter have been stranded on this island for seemingly most of Miranda’s life – she has few memories before their arrival on the island, and even those are vague. (Miranda recalls “Had I not\ Four or five women once, that tended me?” to which Prospero responds, “Thou hadst, and more, Miranda” (1.2.46-8) – obviously Miranda’s earliest memories are foggy at best).
We learn that Prospero is the right Duke of Milan, and that his brother usurped his position with the help of the King of Naples. Now we feel bad for Prospero, and so we can see justification for his desire to re-establish his power and regain his proper title. We learn that Prospero is an avid reader – he values some books over even his dukedom – and so we are inclined to believe that Prospero is not power-hungry, and so his quest for dukeship is possibly a righteous one.
Then things start to get a little weird. Ariel, an airy spirit, shows up and explains that he has carried out Prospero’s wishes. What has Ariel done? He’s the cause of the shipwreck, and has even selected who survived the wreck, who didn’t, and where everyone ended up. Now Prospero seems rather devious – not only has he just committed cold-blooded murder, but he’s in league with some devil-ish spirit willing to commit great atrocities.
But that isn’t quite enough, is it? How does Prospero even command such a powerful spirit? By seemingly being even more powerful and fearsome than it. Prospero suggests that if Ariel should ever mis-step and do something against Prospero’s wishes – Prospero has it within his power to cause him great anguish for an extended (12 years) period of time.
Prospero no longer seems quite the good guy, but rather evil at this point. But then we learn that Prospero actually saved Ariel from a potentially worse fate at the hands of an evil sorceress, Sycorax. Prospero has cared for Ariel, and even promised him liberty after just one year of service. Prospero has essentially a sort of quid-pro-quo, indenture servitude, type of arrangement with Ariel.
So now Prospero maybe straddles the line – he’s done some good things, but then used those good things to justify some less good things. But of course we haven’t even gotten to Caliban, the slave, who is actually some kind of spawn or offspring of Sycorax.
Caliban, it turns out, once roamed this island in his lonesome, and was essentially its master. As Caliban said, “This island’s mine by Sycorax my mother,\ Which thou tak’st from me.” (1.2.332-3). Caliban ruled his roost and then Prospero shows up and takes it all away from him, and to top it all off, forces him into a life of servitude. Caliban goes from being lord of his own domain, to the lowest of the low – a base servant.
But again, Prospero’s actions seem to have some justification to them. Caliban and Prospero initially had a symbiotic relationship: Prospero taught Caliban a language, and gave him berries, and educated him on the seasons and times of day, and in turn Caliban showed Prospero around the island – where the springs were, and which lands were fertile, and which not. But their relationship changed when Caliban “didst seek to violate\ The honour of my [Prospero’s] daughter” (1.2.348-9). Caliban attempted to rape Miranda, and Prospero sought justice by consigning him to a life of servitude.
So Prospero seems to have done a lot of villainous things, but with each villainous behavior, he has some justification. This does not make him a good person – a good person need not justify their actions, most of the time, but it makes his villainy a bit less base and a bit more interesting. The morality of his actions seem to be a bit more gray than would seem initially obvious.
As a side note, I wonder if those books which were more important to Prospero than his Dukedom were tomes of (dark) spells and magic.
[EDIT: ADDENDUM/SYNOPSIS: Prospero causes a shipwreck, but it’s because he was slighted for his dukedom. Prospero lords over an evil spirit, but it’s because he has released the spirit from a worse fate, and has designs to free him completely. Prospero owns a slave – Caliban, but it’s because Caliban attempted to rape Prospero’s daughter. Essentially, Prospero has done a lot of evil, but he seems to have a justification for each thing. This makes him a morally grey villain.]