Who is Elizabeth de Ferrers from The Reckoning and what is their importance?

Elizabeth de Ferrers was King Edward's cousin. Against her wishes, Edward arranged her marriage with Davydd. As an abused woman, Elizabeth was hard to win over..... she was also terrified of being married to a man who was a rebel, knowing that he would eventually fall from the king's graces bringing her with him. Over time, the couple fell in love, but Elizabeth's greatest fears came true. Davydd was executed for treason, after which, Elizabeth was made a prisoner of the English Crown.