I do love faerie stories - and modernised retellings and adaptations are always interesting to read. This book has a variety of fae but mostly focuses on Blue, a kelpie, and his relationship with the human boy, Rin. Blue's form varies between human, semi-human, semi-horse, and horse - but is mostly nearer to human. The scene is set by Rin in a journal entry, where he describes his childhood, the accident that injured him so badly he could no longer ride horses, and the downfall of his mother's business. He also talks of how he met Blue - but the book itself is written quite some time after their meeting, and their relationship is already very much established. Blue actually lives with Rin and his mother, who are fully aware of his fae nature and extremely accepting.
Much of the book is set in the ordinary human realm, with the three main characters struggling to keep the business afloat. As Blue is the only 'horse' that Rin is able to ride, they decide to enter a race to earn some money (and publicity). And while they're preparing for this, Jim comes along. He's another kind of faerie, and he's looking for Blue.
And to top it all off, Rin's mother is kidnapped soon after the big race. This demands a rescue mission, wherein Rin and Blue venture Underhill, to the faerie realm.
This sounds like a very epic fantasy adventure - and it is. But the actual adventure Underhill is a rather small proportion of the book. A much more prominent theme is Blue and Rin's relationship, which becomes increasingly sexually explicit.
There's also some mystery around Rin's father, who he never met. His mother admits to him having some kind of magical heritage, which brings a lot of questions to Rin's mind.
I enjoyed the Underhill journey, but it was disappointingly short. The general relationship between Rin and Blue was rather interesting, but I wasn't keen on all the sexual scenes, honestly. I didn't really feel that they were all that necessary. I actually really liked the kind of day-to-day narrative with Blue; if you've ever wondered what life would be like if you were living with a blue faerie, this book should give you some insight. Overall, I definitely did enjoy this. But it wasn't quite what I expected, and it didn't particularly resonate with me personally or emotionally. 3.5 stars.