Nightstrider

Wren is a nightmare, a manifestation of human fear bound in service to the tyrannical Reverie king Warwick. After she fails a mission and is brutally punished, she throws in with a growing rebellion trying to find a weapon that could end his reign for good.

With a fellow rogue nightmare, a human queen who can cross between the waking world and the dreaming Reverie, and Warwick's own naive son, Wren edges toward a chance to finally break her king's hold, before the boundary between dreams and reality collapses completely. The first book in an epic dark fantasy series spanning two connected worlds.