What a sweet story! Really enjoyed this one! Again, it's Night Huntress World, not a Cat and Bones novella. Cat and Bones appear briefly since the main heroine - Elis - is sired by Mencheres.
Elis has always been a loner. The minimum she does interact with humans is due to her maker who insists she try to mingle in the modern world.
All this changed when she met Blake, a human possessed by a demon making him a killer when the demon takes hold of his body.
Blake had enough all he wants to do is die - killing the demon as well.
Elis is awed by the sacrifice Blake is willing to make for others and as she spends more time with him she realizes she is falling in love with him.
But what use there is in that when even Mencheres can't save him? The only way to kill the demon is to release him into the salt planes AFTER Blake's death.
So all Blake and Elis have is borrowed time.
I loved both Elis and Blake, Mencheres is always a pleasure to read especially once you know him and understand why he acts the way he does. Recommended! Though I think that if you don't know Mencheres, Cat and Bones it will be a little less enjoyable.