The Mortal Bone — Marjorie M. Liu

When the bond Maxine Kiss shares with the demons tattooed on her skin is deliberately severed, the demon hunter is left vulnerable and unprotected. For the first time in ten thousand years, the demons have a taste of freedom. And as the little demons grow more violent and unpredictable, Maxine starts to fear they will lose their minds without her. Reuniting won't be easy, since a greater temptation waits for these hellions: a chance to return to their lives as Reaper Kings, and unleash hell on Earth.