The King's Curse by Philippa Gregory

Fascinating historical fiction about Plantagenet Margaret Pole and her very precarious relationship to the Tudor family during the reigns of King Henry VII and then his son, King Henry VIII.  Married off to a kindly knight, she raises her family in rural obscurity hoping to avoid the horrible fate of her father and brother, both of whom were executed. She and her husband become foster parents for Arthur, the Prince of Wales, and then her life becomes gradually more intertwined in the Tudor Family travails as she develops a close relationship with Catherine of Aragon, and involved in caring for Princess Mary. Rich in detail and flavor, this book adds the perspective of an important player in the Tudor story.