Lady Vivian is the daughter of King Olaf, who came to Camelot with three other kings to sign a peace treaty. Taking advantage of her paranoid and almost insanely overprotective father, another king arranged for Arthur to be enchanted to fall in love with her, hoping that the subsequent duel between Arthur and Olaf when Olaf discovered this 'insult' to his wishes would result in the death of one and the subsequent declaration of war. But, Vivian did not love Arthur and was described as the only woman in the kingdom not to love him. So, the warmongering king had her enchanted as well, making her fall desperately in love with Arthur. Although Merlin and Gwen were able to break Arthur's enchantment, Vivian apparently remained in love with Arthur as she departed Camelot; it is unknown if the spell will wear off over time or she will be forever be under its effects.