The thirteen witches listed here are the Legacy Witches. Being nominated by their mother before them, they inherited more than just the riches and control of the family, they inherited Lasher, the family spirit.
Suzanne of the Mayfair called the Spirit of Lasher, not knowing what she was doing. Doing her bidding for her and doing what he deemed best, led to her death, leaving her only child Deborah orphaned. At twelve years of age, Deborah took control of Lasher, as it would always be with each generation. Lasher would appear to each baby girl and upon her seeing him, would be declared the next witch or legacy beneficary.
Each witch handled their reign and time with Lasher differently. Some loved it and gained all they could from it like Deborah and others suffered greatly from his presence, like Deidre. What they all did not know, was that they were all a part of his cunning plan to create a witch strong enough and powerful enough for him to pass through and become flesh ... the thirteenth witch.