Spirit Wars by A. J. Manney

He has the temper of a dragon. She has the stubbornness to match.

Six months ago, Harper’s world changed forever when her long-lost bonded dragon finally appeared. She’s been waiting that long for Rauk, King of the Dragons, to finally appear. When he does, it’s with all the arrogance, frost, and infuriating authority she expected—and none of the help they need.
With the death of Terron and his gryphon, the ancient guivres have broken free of their cursed forms. Now they’re multiplying, mobilizing, and hungry for dominion. Only the dragons can meet them in the skies, and that means they need Rauk and his kingdom’s help. Harper’s task is impossible: follow Rauk into the heart of the Dragon Kingdom and convince a king who cares for no one, who may have murdered his own father, to join their war and save people he doesn’t care about. He’s the king the realms fear. She’s the one person brave enough to challenge him. Together, they might just save their world…if they don’t kill each other first.