The Sleeping Life — Andrea K. Host

Fallon DeVries has a sister who lives only in his mind. Paying the price of magic gone wrong, Aurienne is trapped watching a world she cannot touch, only able to communicate with her brother while he sleeps. And it's slowly killing him. Fallon and Auri's best chance of untangling their lives is to win the help of a mage of unparalleled ability. But how can they ask for help when the warped spell prevents him from speaking? Besides, Rennyn Claire - once the most powerful mage in the world - is a shadow of her former self: ill, injured and unlikely to recover unless she can hunt down the monster who once tried to make her his slave. But that Wicked Uncle is nowhere to be found, and other dangers, once slumbering dormant, are stirring...