An interesting story. I dislike leaving reviews with little to no criticism but there is not much here that I can find fault with. The characterisations are well done and the reasons for both Mab and Harry's decisions are understandable and fit.
Spelling and grammar are well done and the story flows well. I can't say much on the plot until the direction that you're taking it in becomes more clear but I am definitely looking forward to seeing what comes next.