Mentioned in Blood Canticle (2003), Evelyn is the daughter of Cortland (son of Julien Mayfair) and Barbara Ann Mayfair (daughter of Tobias Mayfair). Because Evelyn is a very powerful witch in the Mayfair family, born with six fingers on each hand, they keep her locked in the attic of their house on Amelia Street. When she is thirteen years old, she is discovered by Cortland’s father, Julien, who finds her mute and wearing mostly rags. He takes her from Cortland’s house and keeps her in his bedroom. Whereupon he cares for her, and she begins to speak, revealing to him that the eventual incarnation of the evil spirit Lasher will attempt to destroy the Mayfair family, as well as most of the world. In time, Evelyn and her grandfather Julien become lovers, which results in her pregnancy with her only daughter, Laura Lee Mayfair.
Laura Lee becomes the mother of Alicia Mayfair, who becomes the mother of Mona Mayfair, the Designée of the Mayfair Legacy and the fledgling of the vampire Lestat, making Evelyn her great-grandmother, whom Mona refers to (particularly in conversing with Lestat) as Ancient Evelyn.
For more perspectives on Ancient Evelyn’s character, read the Alphabettery entries Designée of the Mayfair Legacy, Julien Mayfair, and Mona Mayfair.