What Monstrous Gods by Rosamund Hodge

Centuries ago, the heretic sorcerer Ruven raised a deadly briar around Runakhia's palace, casting the royal family into an enchanted sleep - and silencing the kingdom's gods.

Born with a miraculous gift, Lia's destiny is to kill Ruven and wake the royals. But when she succeeds, she finds her duty is not yet complete, for now she must marry into the royal family and forge a pact with a god - or die.

To make matters even worse, Ruven's spirit is haunting her.

As discord grows between the old and new guards, the queen sends Lia and Prince Araunn, her betrothed, on a pilgrimage to awaken the gods. But the old gods are more dangerous than Lia ever knew - and Ruven may offer her only hope of survival.

As the two work together, Lia learns that they're more alike than she expected. And with tensions rising, Lia must choose between what she was raised to believe and what she knows is right - and between the prince she is bound to by duty...and the boy she killed.