What we love about this concept!
I love the paranormal aspect of the spirit walkers in this one. I love how angsty and heart-rending this one sounds as well. Each book in this series could follow a different pair of lovers from the hunters group, and I think this would be just fantastic!
There are many ways you can take this concept and make it your own. You can focus on different elements of the story, you can add your own particular brand to it, and do just about anything to it. Who do you want to serve? What type of story do they want?