How does Sir Myles change over the course of the novel, Lioness Rampant?

Throughout the story, Myles shows himself to be kind and generous, with a hospitality that can not be matched. In the end of the story, however, another side of Myles is shown. During the rebellion, Myles fights fiercely and brutally. He ignores his own injuries, but only until his friend insists on healing him. Jon feels that this is a good thing, as his temper was so frightful, that they feared what he might do to their prisoners.