"Less than Nothing", Robert Reed

NT F&SF Jan 2006 - modern fantasy
Native American boy Raven Dream is banished from his people. Angry ghost One-Less follows him to ranch of Blue Clad and Stone Face, otherwise known as Edward and Clare. The hidden Lakota people call others demons.

Part of a series, which I haven’t read the other stories. Nonetheless, this novelette was well-written enough to hold my interest.