The Eklyptian Trilogy

What was it like when dragons ruled the world? For Bull it might as well have been a story that held no truth. Bull is a slave, forced to carry out his master's orders. For soon to be seventeen year old Jean, dragons are only in the books she reads. For peace to be restored, Jean must step into their world and rely on dragons to help her - including Bull, an enemy and one of the last of his kind.