Who is Dame Juliana from The Reckoning and what is their importance?

Dame Juliana is a lady-in-waiting at Ellen's court. She loves Bran, but after his death, she in unable to and find peace. Devoted to Ellen, Juliana follows her to Wales, where she attracts the attention of many with her beauty. Juliana, however, has no interest and remains faithful to the love of her life and to her queen. After Ellen's death, Juliana returns to France and later remarries.