MiddlegameMy rating: 5 of 5 stars4.5 stars bumped because, while all of it didn't work for me, the parts that did work were truly wonderful.Alchemy- a seemingly magical process of transformation, creation, or combination.Imagine you're an only child, with an imaginary friend. You find out your imaginary friend, whose voice you hear in your head, is a real person. You find out they live on the other side of the country. You also find out you both have the same birthday and year, and when you finally meet, the same eyes and features. Imagine you're a twin. And when you finally come together, you make something entirely new and different. And dangerous.Roger Middleton and Dodger Cheswich are twins. They aren't twin humans, though; they're twin alchemical constructs. They are called cuckoos (a la Wyndham's brood parasite Midwich Cuckoos) because human parents have adopted and raised them, though at least one set of those parents doesn't know that the cuckoos aren't human. But that's okay because Roger and Dodger don't know what they are and what they can do yet, either.An unusual aspect of this book is that we don't even meet Roger and Dodger (the central characters!) until more than fifty pages into the story, and we don't see what they can do until more than halfway through the book. Although, maybe that last part is a good thing. What they can do may not be beneficial for the world. Roger and Dodger are written with exquisite care, and for me, the best part of this book is their maturation as individuals, their sibling relationship and their character arcs. Roger and Dodger aren't "regular people" in the biologically-born sense but they are real and feeling people who are counted, like their brethren, as disposable by their creator. (There's a whole powerful subtext here that runs throughout the book in which alchemy could be equated to religion and religions may be too quick to discard those who are "imperfect.") Erin, a character who surprised me in that I grew to like her in spite of her viciously thorough side, gives us a poignant sense of what it's like when one alchemical twin is lost. In addition to giving us a story of two people finding "their other half" and figuring out who they are, the novel gives us the story of what happens when you meet your maker and your maker is a terrible person.Looking at what didn't work as well for me, the alchemy itself was rather sketchy (seemingly not based on gnostic alchemical-doctrine?), as was the application of quantum entanglement on a macroscopic scale. The non-specific fourth-dimensional math, and the timeslip elements of the story, were never really explained in a grounded way for the reader. Still, the story kept me engaged. I found it read like a perfect amalgam of Seanan McGuire (fantasy) and Mira Grant (horror, since there's a reason there's a hand of glory on the cover, folks) writing styles.Middlegame, middlegame... This is a book where I have contemplated the definitions of central themes (alchemy, cuckoos, manifestation, entanglement) including that title, which means the phase of a chess game, after the opening, when all or most of the pieces and pawns remain on the board. It leaves me wondering if there is space for a prequel. And a sequel. I'd be happy to see more of these characters.Favorite quote:"Stick and stones may break my bones but words will never harm me? Words almost never end that way. Words can be whispered bullets, quick when no one is looking, and words don't leave blood or bruises behind. Words disappear without a trace. That's what makes them so powerful. That's what makes them so important."I received a paper Advance Reader Copy and a Digital Review Copy of this book in exchange for an honest review.