William "Billy" Maximoff is the son of Wanda Maximoff and Vision, and the younger twin brother of Tommy Maximoff. Created and raised within the Westview Anomaly, he, along with his brother, were targeted by S.W.O.R.D. and eventually captured by Agatha Harkness. During the Battle of Westview, the brothers were freed and helped defeat the S.W.O.R.D. agents. Following the battle, Wanda dispelled the Hex; however, Billy's soul jumped into the recently deceased body of William Kaplan. Billy, who became amnesiac, then lived for three years as William Kaplan. However, upon studying witchcraft, he sought to find Tommy and embarked on the Witches' Road alongside Agatha Harkness and her new coven.