Book of a Thousand Days by Shannon Hale. If you haven't read this book yet, do!
Book of a Thousand Days is based on the story Maid Maleen by the Brothers Grimm. It's the diary of Dashti, lady's maid to Lady Saren of the fictional realm Titor's Garden. The two girls are imprisoned in a tower by Lady Saren's father for her refusal to marry Lord Khasar whom she hates and fears. During their imprisonment, both girls undergo a slow transformation of spirit that colors their life and decisions thereafter.
I admit that when I first started reading Book of a Thousand Days, I wasn't sure what I thought of Dashti's voice. The book is written in first-person, which usually gives me pause as I decide if I like the MC, but it hooked me. Dashti's personality was vivid and sturdy from the very beginning. With humor and strength, this girl was built to withstand gales in both her story-world and the literary world at large.
Shannon Hale did a wonderful job making me sympathize with the characters, to the point that Dashti's choices seemed like my own if I were in her place. I became invested in her growth as a character and eager to see her discover more past her limited view of the world. I also appreciate that Dashti wasn't traditionally pretty, a stark contrast to the lovely, but frightened, Saren. Readers could see the flaws in both of the girls and very readily in Saren, in spite of her beauty. (There were times I hated Saren too, I must admit.)
I thoroughly hated Lord Khasar and was as disgusted by him as Dashti herself was. I also absolutely loved Khan Tegus. He was a man who I would pick for myself, and I don't often find that in YA novels. This guy is pure gold. Honorable, noble, compassionate, gentle and caring. He held true to the personality the author had given him all the way to the end of the book. I appreciate that she didn't change him or spoil him just to create drama for the two girls. He was also fully-formed. He had his own problems, his own desires, his own responsibilities. He wasn't a flat character created for the MC to swoon over.
Yes, there was romance in this book. I read and enjoyed a romantic sub-plot that was so twined with the main plot that it couldn't be separated. That's because I was truly fond of both characters involved. The romance was slow-building, formed from a genuine connection and spiced up by attraction and admiration. It was an incredibly sweet, incredibly moving romance and I wish I could find more like it.
As for the world-building, I questioned a lot whether the culture was invented or just unfamiliar to me, and that means it was good. Because it reads from Dashti's perspective, we get a strong view of her belief system and her values, as well as how she changes from the beginning of the book to the end.
My rating on Goodreads for this book was five stars, but it merits more.