I've read four books by Kiersten White before and while I found them pretty good for the YA genre, let's be honest and acknowledge that it's not exactly high praise to be pretty good for the YA genre. Still, I found her characters compelling and memorable, which is saying something when you see all the books that I burn through. 
 And I Darken is not at all what I expected. I picked up the book, read the book flap description, and thought - well, White's writing has been entertaining before and I do love reading about Romanian history and the region (for an adult urban fantasy series where you can read about other very different versions of Mircea and Radu, try Karen Chance) so I'll read this. I was not expecting to be blown away by this book. I was not expecting the sheer beauty and complexity of this story, the unapologetic presentation of its characters and above all else, the brutality of history that is usually softened or sometimes even absent completely when you read historical fantasy/fiction, especially in YA. 
 To be honest, I feel like this book is classified as YA mostly because of the ages of the characters...but if you're going by that rule, does that make Game of Thrones YA too? If anything, I think many teenage readers would not appreciate the book as much as adult readers do; when compared to the current marketing and style of other books in the genre, I think younger readers will find the book too "boring" because you don't get easy depictions of good and evil. The characters here all have their strengths and their flaws. In each case they are driven by motivations that they don't necessarily understand. 
 Like many others, I found myself loving Lada for her strength and yes, brutality (finally a character who lives up to its cover description!), her need to gain power and security in a world dominated by ambitious men. This book easily could have turned out to be a C grade version of itself, where the "brutal" princess is brutal only in description and it turns into a cringeworthy love triangle and power/politics are just sprinkled into the story as an attempt to give it some flavor. Instead, what you get is a nuanced depiction of a sibling relationship that encompasses everything from rivalry to possessive love. The love story, so to speak, is passionate and significant, but definitely not the kind of romantic that you'd expect out of a YA novel. Quite frankly, nothing about this book is what you'd expect from a YA novel and yet it is a great example of why I still read them.