A fun piece of knowledge for an avid reader of fantasy. Thee, thou and thine are popular in stock fantasy. They are, apparently, almost always incorrectly used.
Even though Wikipedia should be used with care, this article conforms with the literature I have available.
Primarily used to denote familiarity, or by a superior to an inferior, the usage of these words in fantasy becomes rather hilarious. Rather than use the formal 'you' our heroes deliberately insult kings, queens and fair ladies all around them.
I can only quote Sir Edward Coke: "I thou thee, thou traitor!"