Crystal Kingdom by Amanda Hocking

Second Hand 

Cast out by her kingdom and far from home, she's the Kanin people's only hope.

Bryn Aven-unjustly charged with murder and treason-is on the run. The one person who can help is her greatest enemy, the gorgeous and enigmatic Konstantin Black. Konstantin is her only ally against those who have taken over her kingdom and threaten to destroy everything she holds dear. But can she trust him?

As Bryn fights to clear her name, the Kanin rulers' darkest secrets are coming to light... and now the entire troll world is on the brink of war. Will it tear Bryn from Ridley Dresden, the only guy she's ever loved? And can she join forces with Finn Holms and the Trylle kingdom? Nothing is as it seems, but one thing is certain: an epic battle is underway-and when it's complete, nothing will ever be the same...