A Fool's Errand — Odette C. Bell

They're on the run -- from Garl, from the Night, from everyone.
With no friends to rely on, they only have each other. But will it be enough? Especially when secrets have come between them.
….
Yang knows Yin's hiding something from him, and the more they travel together, the easier it is to guess: is Yin the Savior? If she is, their journey will only become more perilous. The Night will hunt her mercilessly, and Garl's men will never stop ….