How was Sauron corrupted, and what gave him the power to oppose any and all of the Maiar? In what Tolkien describes in The Silmarillion as the Days Before Days, Sauron’s first name was Mairon.

Part of this sinister reputation is specifically attributed to the fact that Sauron could take on many forms, both of an attractive and less attractive nature. "The Silmarillion" describes him at ...