Gormlaith Gaunt murders her sister Rionach and brother-in-law William in an attack that sets the couple’s cottage, Ilvermorny, on fire. William and Rionach’s daughter, Isolt Sayre is removed by the fire by her aunt and taken to live with her in Hag’s Glen.
Gormlaith’s actions are motivated by prejudice for Muggles and wizarding folk of impure blood. She disapproves of how her estranged sister and her sister’s husband are raising their daughter with no regard for the concept of the superiority of pureblood witches and wizards. Gormlaith seeks to raise Isolt with a different understanding of the world and to impart her with an appreciation for her duty to choose a pureblood spouse and have pureblood children.
Gormlaith leeds Isolt to believe that her aunt is merely a heroine who rescues the her niece from a tragedy, but Isolt eventually figures out the truth (Pm).