This is one of the Five Hundred Kingdom series that Lackey writes for Luna. The setting has "Godmothers" protecting people and Kingdoms from a force of nature called "The Tradition" The Tradition can't be reasoned with but you can tweak the circumstances of what is happening to confuse it. This one spins the story of Sleeping Beauty on its ear and I think makes a really good story about it and it has the plus of giving the princess something to do. I really like the books in this series and I hope there will be more.

