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

Elizabeth de Ferrers is a cousin of King Edward. Edward gives her in marriage to Davydd, a marriage she does not want. She has been abused and does not wish to be tied to a rebel who will eventually fall from grace, bringing her with him. Davydd wins her over easily by showing her simple kindness, and soon he finds that he loves her too. Davydd claims that if she marries him, she might one day wear a crown, words that haunt him as he is lead to his death for treason. After Davydd's death, Elizabeth is a prisoner of the English Crown.