Master of Dragons — Margaret Weis

They were both the offspring of Dragon magic, one raised in court, the other in hiding....but the link that exists between them will not be broken by mere distance, and the duality of their origin will unlock new hope for a return to peace and safety. Now two renegade dragons have hatched a plan to enslave all mankindan act in direct contravention to all the precepts of the Dragon parliament. With an army of crazed demi-human/ dragons, they threaten the world order. It is up to the two brothers (separate and together) and Draconas, the special emissary of the Parliament, to restore the status quo between Dragonkind and mankind, even if by doing so, Dragonkind seals its own eventual doom.