I received an ARC from the author in exchange for an honest review.

I don't know where to start. This book was everything I was hoping it would be, and then some.
"Slippery Creatures" and "The Sugared Game" were some of my favourite reads last year: I read them, I freaked out, I re-read time and time again because they were absolutely stunning, masterfully constructed with a cast of characters I would die for. I was pretty sure I was going to love "Subtle Blood" with my whole heart (I haven't yet read a KJ Charles novel that I didn't thoroughly adore). I was expecting action and romance, spy shenanigans and probably a lot of lies, shifty characters and daring escapes and last-minute reveals. And that was all there (even though, to a lesser degree than what we saw in "The Sugared Game"). I was not, though, expecting this novel to be so sweet and soft, riddled with soul-wrenching conversations and moments so delicate and precious that I literally had to take a breather to calm myself down and not have my heart jump out of my chest.
The action was all there (especially in the last half of the novel) as were the shocking reveals, however there was a slightly different atmosphere and feeling to this book. It was softer, less gritty at times, less the glittering Twenties atmosphere of the second book, and more gentle, more thoughtful. And I think that was completely due to the way both of the main characters have changed.
We left Kim and Will, at the end of book two, with Kim having lost his job and life purpose, and Will having finally gained a sort of upper hand with him: he was feeling hopeful but still a bit heedful about his future relationship with a man who lies and lies and lies.
In "Subtle Blood" the tables have turned though, and I won't say how, but this time it is Will who has to deal with his past, his way of thinking, his coping methods. And it was glorious to see. I don't know how many times I've said this but it's worth repeating: I love Will Darling with my whole heart. He's stubborn and unshakable, strong and clever, he'll stand up for himself and the ones he loves with fists and rude words, and he'll fight anybody who tells him what to do. I loved that about him during the first two books, and also during the events of this third novel, but here KJ Charles adds a layer to his personality, a vulnerable side, that I hadn't predicted and oh my god, not only did it confirm why I love him so damn much, but it also made me want to crawl inside the book and hug him.
His relationship with Kim was something glorious (and precious) to witness: they've made progress, they've finally started to understand and know each other, really know each other. And each time they were on page together... it was sparks and fireworks, chemistry and complicity and deep understanding. They were truly each other's lover and friend, confidante and partner-in-crime.
Maise and Pheobe have their own glorious moments here (I love them, so so so much) and the whole cast of characters truly shine (especially Peacock: I need a sour henchman too) and make this novel unforgettable.
KJ Charles is a formidable writer and plotter: I know that finishing a trilogy that's so closely intertwined was hard work and she not only managed to do a spectacular job at tying up the loose ends and completing character ARCs, but she also constructed a story that was thoroughly addicting and very hard to put down. The ending was satisfying and glorious and I'm so so looking forward to reading KJ Charles' next literary adventures.
I'm feeling quite bereft at the moment: I think I need to re-read. And probably highlight some passages and also entire scenes, and tattoo the ones that completely wrecked me on my forehead. Yes, I'll do that now.