Lucy Webster, sole survivor of the Webster family famed for their unique magic using spiders to weave paper and create flawless grimoire copies, witnessed her family's slaughter during the Webster Tragedy eight years ago. Emerging from self-imposed isolation just in time to see werewolves massacre her kin and steal their spiders, she was spared but left deeply traumatized and distrustful of other mages, fueling her relentless pursuit of the truth. Her older brother, Seth Noel – cast out by their father for lacking magic and explicitly replaced by Lucy as heir – cared for her afterward, adding to her emotional scars.

Enrolling at the College partway through primary school, Lucy maintains a cynical outlook and emotional distance, observing others while rarely smiling, earning a "problem child" reputation. Though irritated by her roommate Chise Hatori's politeness and averse to casual talk, she demonstrates underlying compassion, assisting Chise with dorm logistics and criticizing those like Zoe Ivy who ignore others. She strategically avoids enemies while learning what matters to people.

Her resilience surfaces when an unknown entity drains her life force during a camping trip, leaving her unconscious for ten days. Later, she identifies creatures attacking her and Chise as the same ones responsible for her family's slaughter. This hardens her resolve to hunt them, even using herself as bait. Her investigation reveals Lizbeth Sargant orchestrated the Webster Tragedy to eliminate witnesses after creating a forbidden grimoire copy.

Her relationship with the exiled Seth Noel remains strained; she initially refuses his financial support and suspects his involvement. However, they begin mending their bond during the College lockdown when Seth checks on her recovery. Lucy forms cautious alliances, joining a pact to protect Zoe Ivy's demi-gorgon secret and distrusting Philomela Sargant due to her family's espionage and role in clan ruin. Despite her hardened exterior, she acknowledges Chise's unwavering support, though criticizes her self-sacrificing nature.

Lucy sustains herself through part-time work at the Discard Tower, relying on her hereditary magic to control spiders for crafting enchanted paper and books. Her journey shows a shift from isolation toward reluctant collaboration, driven by her quest for justice and closure regarding her family's legacy.