Flowerheart by Catherine Bakewell

Clara’s magic has always been wild. But it’s never been dangerous. Then a simple touch causes poisonous flowers to bloom in her father’s chest.

The only way to heal him is to cast an extremely difficult spell that requires perfect control. And the only person willing to help is her former best friend, Xavier, who’s grown from a sweet, shy child into someone distant and mysterious.

Xavier asks a terrible price in return, knowing Clara will give anything to save her father. As she struggles to reconcile the new Xavier with the boy she once loved, she discovers how many secrets he’s hiding. And as she hunts for the truth, she instead finds the root of a terrible darkness that’s taken hold in the queendom—a darkness only Clara’s magic is powerful enough to stop.