Diana is an immensely powerful "weaver witch" and former historian who possesses the rare ability to timewalk. Having spent much of her life avoiding magic due to the traumatic murder of her parents, she now actively studies spell architecture to master her growing abilities. She is fiercely independent and protective of her expanding family, often clashing with her husband's overprotective instincts.

Matthew is an ancient vampire scientist burdened by a dark past and the genetic affliction of blood rage, which causes violent impulses. He operates as the lethal enforcer for the de Clermont family but actively attempts to manage his predatory instincts. He applies his scientific expertise toward understanding creature genetics, hoping to secure a safe future for his wife and unborn children.

Sarah is a skilled witch and Diana's aunt who is suffering profoundly from the sudden loss of her partner, Emily. Known for her fiery temper and stubbornness, Sarah retreats into her sorrow but eventually finds purpose in teaching Diana the intricacies of spell architecture. She acts as a blunt but loving anchor for her niece.

Baldwin is the autocratic head of the ancient de Clermont vampire clan and a high-ranking member of the Congregation. He resents Matthew's independence and refuses to recognize Diana's adoption into the family by Philippe. Baldwin operates with an iron grip, prioritizing the survival of the family name over individual happiness.

Benjamin is Matthew's disowned vampire son, harboring a centuries-old vendetta against the entire de Clermont family. Afflicted with blood rage, he operates in the shadows, conducting horrific experiments on captured witches in a twisted attempt to breed vampire-witch hybrids. He searches relentlessly for the Book of Life to secure total dominance.

Gallowglass is Matthew's massive, blond vampire nephew. Tasked by his grandfather Philippe with watching over Diana, Gallowglass serves as her steadfast, silent protector. Unlike Matthew's commanding approach, Gallowglass offers gentle encouragement and respects Diana's autonomy while ensuring her physical safety.

Peter Knox is a powerful witch and a former member of the Congregation who actively seeks the Book of Life. He is deeply prejudiced against other creature species and uses lethal force to achieve his goals, bearing responsibility for multiple tragedies within Diana's family.

Gerbert is a powerful, ancient vampire and a leading member of the Congregation. He serves as a long-standing political rival to the de Clermont family and uses his authority to pressure them, taking Ysabeau as a hostage to ensure their compliance with Congregation laws.

Marcus is Matthew's vampire son and the Grand Master of the Knights of Lazarus. He has a laid-back, progressive attitude that frequently conflicts with the traditional, autocratic methods of older vampires like Baldwin. He advocates for modernizing the family structure and pushes Matthew to separate from Baldwin's control.

Fernando is the vampire mate of the late Hugh de Clermont. Never officially accepted into the de Clermont family, he operates quietly in the background, serving as a vital support system for the household. He steps into caretaker roles willingly, managing the physical household while offering emotional comfort to grieving members.

Jack is a young artist who was taken in by Diana and Matthew as a human child in 1591. He surfaces in the present day as a vampire afflicted with blood rage, having been turned centuries prior to save him from the plague. He struggles to manage his violent impulses, channeling his frenzied energy into drawing and music.

Ysabeau is Matthew's vampire sire and the matriarch of the de Clermont family. She is highly pragmatic, collecting intelligence even while held hostage. Ysabeau formally accepts Diana as her daughter and attempts to instruct her on the secretive, politically dangerous ways of vampire society.

Chris is a human molecular biologist and professor at Yale, as well as Diana's best friend. He provides the scientific resources and laboratory space necessary for Matthew to study creature genetics and blood rage. Chris brings a logical, cooperative approach to a problem usually shrouded in supernatural secrecy.

Miriam is a sharp, analytical vampire research scientist and one of Matthew's closest confidantes. She actively assists in researching creature DNA and blood rage. Miriam speaks her mind freely, refusing to coddle Matthew's need for secrecy when scientific progress is at stake.

Andrew is the vampire king of London who oversees a diverse flock of creatures in his city. He operates independently of traditional vampire politics and actively rejects Matthew's authority, though he is biologically Matthew's grandson through Benjamin's line.

Emily is Sarah's late partner and Diana's aunt who died following an encounter with Peter Knox. Even in death, she remains present at Sept-Tours as a spectral observer, mourning her separation from the living world while continuing to watch over her family.

Philippe is the deceased patriarch of the de Clermont family and the original founder of the Congregation. Though dead, his influence remains immense. He officially adopted Diana as his blood daughter in the past, an act that forces the current family to reevaluate her status.

Phoebe is a human historian and Marcus Whitmore's fiancé. She adapts quickly to the supernatural world, offering her historical expertise to assist Diana in researching the missing pages of Ashmole 782 while preparing for her own transformation into a vampire.

Linda is the leader of the London Coven and part of Andrew Hubbard's extended creature family. She helps Diana connect with her witch identity and assists in tracking down missing historical artifacts.

Vivian is the high priestess of the Madison Coven. She supports Sarah through her grief and acts as a liaison between the local witches and the Congregation regarding Diana's magical activities.

Rebecca is Diana's deceased mother, a powerful witch who was murdered due to her abilities. She appears as a specter, observing her daughter's progress and leaving behind grimoires that guide Diana's magical development.

The Goddess is a divine entity with whom Diana struck a powerful bargain. She occasionally intervenes to force Diana into action, embedding a magical arrow in her as a tool for delivering justice.

Marthe is Ysabeau's vampire companion and servant. She operates as a steady, nurturing presence within the de Clermont household and assists with the daily care of the family.

Satu is a witch member of the Congregation who shares Diana's rare status as a weaver. She fears persecution for her abilities and views Diana's openness about their shared magic as a severe threat to her survival.

Janet is a witch who steps into a Congregation seat. She reveals her own complex heritage to support Diana's arguments against the covenant, demonstrating that cross-species reproduction has historical precedent.

Rebecca is one of the newborn twins of Diana and Matthew. Named after Diana's mother, she predominantly exhibits her vampire heritage and requires supplemental blood for sustenance, causing anxiety for Matthew.

Philip is the newborn son of Diana and Matthew. Named after Matthew's late father, he exhibits red hair and shows early signs of magical potential, reflecting his witch heritage.