Frederick is Cassie's tall, dark-haired vampire roommate who was turned in the 18th century. He navigates 21st-century life with her help, striving to live ethically by avoiding feeding on humans and developing strong feelings for Cassie.

Sam is a lawyer and Cassie's loyal best friend since middle school. He offers Cassie support, both legally and emotionally, alongside his husband Scott, providing a safe haven when Cassie is in need.

Reginald is Frederick's fun-loving vampire friend who inadvertently caused Frederick's long coma but also took care of him during that time. His friendship with Frederick is complex, as he plays a role in Frederick's moral development and adjustments to modern life.

Edwina is Frederick's mother and serves as an antagonist with her traditional vampire views, pushing for an arranged marriage for Frederick. Despite her controlling nature, she maintains a complicated maternal affection for her son.