Joanna’s older sister and a protagonist who works in Antarctica and discovers her ability as a Scribe, balancing her independent lifestyle with her connection to her family.

A third protagonist raised in the Library by Richard Maxwell and Dr. Maram Ebla, characterized by his sheltered upbringing and journey toward independence and community.

Nicholas’s controlling "uncle" and the antagonist whose interest in preserving the Library’s legacy drives him to manipulate those around him.

A complex secondary character who has ties to both the Library and Joanna's family, marked by her alias choice and deep knowledge of magical texts.

Joanna and Esther’s affectionate mother, originally a nanny, who has strong motivations concerning her daughters' safety and the family’s magical legacy.

Nicholas’s bodyguard, known for his taciturn nature and complex backstory, who forms a significant friendship with Nicholas and a budding romantic connection with Joanna.