Mary novels (Cynthia Hand)

"Welcome to Renaissance France, a place of poison and plots, of beauties and beasts, of mice and ... queens? Mary is the queen of Scotland and the jewel of the French court. Except when she's a mouse. Yes, reader, Mary is a shapeshifter in a kingdom where Verities rule. It's a secret that could cost her a head--or a tail. Luckily, Mary has a confidant in her betrothed, Francis. But things at the gilded court take a treacherous turn after the king...