Stain by A.G. Howard
Stain is set in a fantasy world where one kingdom in the past was split into two. Now the two kingdoms are day and night, and they have been at war for as long as anyone can remember. But now may be the time for the two to come back together, after all, the beginnings of the prophecy have started to be fulfilled. A night princess was born to the day royalty and a day prince was born to the night royalty. All they have to do is come together to fulfill the prophecy and rejoin the two kingdoms... Except it can never be that easy, can it? When you throw in an evil stepmother and stepsisters, along with a lot of magic as well as nefarious creatures? Definitely not an easy task.
The writing and tone are magical, really truly feeling like you are reading a fairytale, and not just some modern rendition. I can't emphasize enough how much I loved this book. Please, please read it!
Here's the real synopsis:
"Once upon a nightmare, her fairy tale begins...
This high-fantasy gothic fairytale, inspired by Hans Christian Andersen’s The Princess and the Pea, is set in an alternative medieval world split apart by magic. To win back her kingdom of perpetual day, save her night prince, and reunite the sun with the moon, a princess incapable of speech or sound must prove herself everything a traditional princess is not: tough enough to sleep on a bed of nails, and loud enough to be heard without a voice."