The Iron Crown

The third and final installment had a bit of a different feel, taking place outside of the Sidhe, and focusing on the Slough - the magic-less residents cast out of the fae courts into the Wyld when they split centuries before. Kieran is a human brought into the sidhe by Lugh, the youngest son of Mab. He's also the bearer of a magic belt gifted by Mab that turns him into a raging bear, called a berserker in the book. The book takes a lot from Nordic lore and Kieran himself is alluded to be of Viking blood.
I felt that the characters maybe weren't as developed or as interesting as the previous books. Kieran and Lugh have been the main parts of The Hunt of fae lore for centuries before this book takes place so it doesn't have the same strangers-to-lovers plot the first took books have so doesn't have the same tension. We don't really know why they two haven't admitted their love, though Kieran seems to have some apprehension because of Lugh being a prince. Nothing a single conversation couldn't fix.
It was interesting to learn more about the Slough people and the events that were occurring concurrently with the second book, but I felt overall that it just didn't have the same quality of development.