Avaritia

If there's one thing Verity will consistently do, it's spontaneously make terrible decisions.
Sometimes they work out well—so far, smuggling her rescue cat into the shadow realm has been a great success—but more often than not, she ends up with a bigger mess to clean up than she started with.
If there's one thing Theon will consistently do, it's plot his brother's demise after losing his spot in the line of succession to King Allerick. It has yet to work out well for him, but there's a first time for everything, right?
Especially now that Theon has got himself an ex-hunter of his own to feed from, and he's stronger than ever.
But Verity isn't going to let Theon get away with his treasonous ways, not when he has so much to offer the shadow realm. For the first time, someone believes that Theon has the capacity to do good in the world.
If only he believed her.
Avaritia is the fourth book in the Shades of Sin series, featuring humans and their not-quite-so-human partners. Each book is a standalone, but best enjoyed in order. For mature listeners.