Sons of Ymre: Erik by Lilith Saintcrow

Long ago, there was a mad god who almost destroyed the world.
And he is still out there, waiting…

On a cold winter’s evening, Liv Stellack escapes a bad date…and walks straight into nightmare. Kidnapped and held without ransom, she’s ready to use every trick in the book to escape. But her captors aren’t criminals, they’re Sons of Ymre, hunters of the unclean things living in the cracks of sanity and dreams—and Liv is a valuable tool in their war against the Mad God.
Erik knows the beautiful woman they’ve rescued can’t possibly understand the danger she’s in, or the fact that she’s being held for her own protection. Some things can’t be explained, only shown; he and his fellow Sons have to keep their precious potential alive long enough for the days to lengthen so she can be transported to another temple and learn how to fight an evil older than recorded history.
But treachery lives in the Mad God’s chosen, and it’s soon obvious that one of the Sons can’t be trusted. Fleeing for their lives, Liv and Erik must make an uneasy alliance, depending on each other to reach tenuous safety.
That is, if the monsters don’t get them first…