Who is Nell de Montfort from The Reckoning and what is their importance?

Nell de Montfort is the Countess of Leicester, wife of Simon de Montfort, sister of King Henry and King Richard. She is exiled in France after the death of her husband. Queen Marguerite of France becomes her close friend and ensures that her needs are met. Nell loses a son and husband at Evesham, loses a son to fever, and sees a son excommunicated from the church for murder. Her only remaining son, a priest, is hunted by King Edward, and her only daughter has no hopes for marriage because they have no lands to offer as a dowry. She wants to see her daughter married and protected before she dies, so she fights her deteriorating health. Llewelyn honors his betrothal to Ellen and Nell dies peacefully.