Dragon princess

Frank Blackthorne, a thief on the run from a band of demon-worshiping cultists, is hired to save the Princess Lucille from a knight-eating dragon in return for riches, glory, and an escape from the cultists after his blood. But why would anyone hire a thief to rescue a princess? Frank is in no position to refuse, but soon everything turns out worse than he could have imagined. Due to some wildly misapplied magic, Frank is in Princess Lucille's body, she's in the body of the dragon, and they have to team up against thugs, slavers, elvish bookies, and a host of other baddies to set things right.