I'm Afraid You've Got Dragons

I'm Afraid You've Got Dragons by Peter S. Beagle

Dragons are common in the backwater kingdom of Bellemontagne, coming in sizes from mouselike vermin all the way up to castle-smashing monsters. Gaius Aurelius Constantine Heliogabalus Thrax (who would much rather people call him Robert) has recently inherited his deceased dad’s dead job as a dragon catcher/exterminator, a career he detests with all his heart in part because he likes dragons, feeling a kinship with them, but mainly because his dream has always been the impossible one of transcending his humble origin to someday become a prince’s valet. Needless to say, fate has something rather different in mind…