Lizbeth Sargant leads House Sargant under the Rickenbackers. Her father selected her as heir in youth due to innate talent. Facing pressure for an heir, she married, bore a son, Adam, and likely poisoned her husband soon after. She entrusted Adam's care to a wet nurse, engaging with him only when he obeyed. When Adam helped prisoner Iris escape and they later had a daughter, Philomela, Lizbeth dispatched assassins. The retrieval led to Iris's death and Adam's suicide. Philomela and her artificial fairy companion, Alcyone, were captured. Lizbeth erased Philomela's memories of her parents and cursed Alcyone to prevent comforting Philomela, restricting her solely to task assistance.

Lizbeth raised Philomela as a tool and heir through sustained physical and psychological torment: frequent slapping, verbal degradation, and dungeon confinement for failures like slow memorization. She dismissed Philomela's achievements and interests as useless disappointments. Her cruelty extended beyond family; she employed poachers to kidnap a werewolf couple's cubs. She blackmailed the parents by threatening the cubs, forcing them to slaughter the Webster family and steal their spiders. Child Philomela was forced to witness the massacre. Despite compliance, Lizbeth kept the cubs captive for years, even after the female werewolf failed to kill young Lucy Webster.

Later, Lizbeth sent Philomela to a magical college with the dangerous Testament of Carnamagos grimoire. She tasked Philomela with draining life-energy magic from students and staff, promising to use the power to resurrect her parents. This left victims like Lucy Webster and Professor Simeon Paladihle comatose. Lizbeth also ordered Philomela to spy on threats. When Lucy enrolled, Lizbeth directed the werewolves to kill Lucy and her brother, Seth Noelle. Fearing exposure, Lizbeth tried to withdraw Philomela, but the headmistress refused. She sent a message via Alcyone, berating Philomela for friendships and demanding task completion.

When the wounded female werewolf returned from a failed assassination, Lizbeth pretended to agree to reunite her with her cubs. Instead, she activated a skull-implanted curse, rendering the werewolf feral and controllable, then ordered her to assist Philomela's escape from college. After Philomela, corrupted by the grimoire, retrieved it, Lizbeth coldly ignored her deteriorating state and questions about her parents. Lizbeth prepared a ritual to resurrect Adam, intending to sacrifice Philomela. She summoned the Treader of the Dust entity and mocked Philomela's lifelong obedience. The ritual was disrupted by Chise Hatori and allies. Enraged, Lizbeth merged with the grimoire, attacked the intruders, and killed Alcyone as she shielded the werewolf. She tried manipulating Philomela to halt the ritual's reversal but was killed by a freed werewolf cub. Her final act was refusing to explain the Webster massacre.