In the eyes of any sane person, they're not evil and usually the things they do are for the greater good, in their opinion. (I'm excluding people like Mira hindly and Fred West in this because I did say sane person). Write a story from the perspective of the evil characters in your favourite book... What was Sauron thinking? Did Voldermort have a good side? We know Darth Vader wasn't all bad because he redeemed himself in the end but what about the Emperor? Was it just a scheme that got out of hand and out of his control?