Sun and Moon, Ice and Snow by Jessica Day George
The lass is the last born daughter to a poor woodcutter and his wife. Her parents are so dismayed at the thought of another female mouth to feed, that they refer to the girl only as the pika. In such wilderness of the North it is dangerous to not have a name, as trolls would love to seize the opportunity to snatch up such a vulnerable child. But one day the lass changes her fate when she frees a white reindeer. In thanks the beast gives her two gifts, a name and the ability to understand the speech of animals. However, the second gift seems to turn against the lass when a great white polar bear comes to her home, demanding that she come with him to his palace farther north. The conditions are that she must remain with him for one year, then her family will be rich and she can go home. Can the lass keep her promise or will she destroy everyone's chances of a new life when she uncovers a mysterious secret?