One Good Knight by Mercedes Lackey

This is the second in Lackey's Five Hundred Kingdoms series. They both have fairy tale themes, but with a twist. In The Fairy Godmother, the first, a young girl is made a servant by her wicked stepmother and stepsisters, and all is set up for her to be a Cinderella story. Unfortunately, the prince is only two years old...so what happens then? The Tradition, a force which recognizes fairy tale situations, is at work in the Five Hundred Kingdoms and characters like Godmothers, Champions, Dragons, Sorceresses, Wizards, and Princesses are important in working the Tradition to their advantage

In One Good Knight, Princess Andromedea is nothing like her mother, the powerful, beautiful Queen. Andie loves to read and learn, particularly about the Tradition, and her sweet nature has made her a favorite of the castle Guard. When a Dragon appears, a plan is made to sacrifice a virgin each week to keep it from destroying the kingdom. When gossip says that only the daughters of the Queen's enemies are being sacrificed, Andie finds herself the next sacrifice to the Dragon. After she is tied to the post, and the Dragon approaching, a Champion appears and the Dragon flies away. Knowing that she cannot return to the castle, Andie follows the Champion, and they begin a search for the Dragon's lair. Since the Tradition encourages Princesses to fall in love with Champions, Andie and George, the Champion, swear a blood oath as siblings before George will remove his helmet, since neither wants to fall in love at all. When a passing Unicorn reveals that George is actually Georgina, since a spell put on the border would not allow any man to come in and slay the Dragon, they realize that all is not as it should be. After finding the Dragon's castle, with 2 brother Dragons and a large group of the supposedly-sacrificed virgins, they begin to use other elements from the Tradition to overthrow the Queen and her wicked advisor.

Lackey tells a fantastic story. I love the fairy tale elements, and the frequent warnings that the Tradition likes tragic endings just as well as happy endings. The Fairy Godmother Elena, from the first book, makes an appearance in this one, but reading them in order is not necessary. It is fantasy, but it is a world that we have all been familiar with, once upon a time...