Erebus is a demon known by various names, plotting to regain his power and crown from the human realm. He is a central antagonist with a complex history and deceives Bree into bargains while training her.

Nick is one of Bree's close companions, initially believing he is the Scion of Arthur, who becomes deeply involved in the magical world. He navigates personal revelations about his heritage while trying to dismantle the oppressive structures of the Order.

Zoe and Elijah are twin balanced cambions and allies of Bree, initially following Erebus. The twins face racial challenges in the human realm and struggle with their demon side, with Zoe starting to question Erebus's motives.

Mariah is a fellow Rootcrafter and key to Bree's introduction to Rootcrafting, providing crucial support and insight from their perspective. Aunt Lucille, Hazel, and Valec support Bree with their own unique contributions to the magical community.

William, a healer and close friend to Bree, provides essential support and advocacy against the Order's injustices. Larkin helps Bree and William during pivotal moments, sharing in the aim to challenge unfair systems.

Natasia is Selwyn's mother and a powerful Merlin, grappling with her demonia and a complicated past within the Order. Her connection to Bree’s mother and dedication to her promises significantly influence her decisions.

Selwyn is a powerful Merlin and Nick's bonded Kingsmage, deeply connected to Bree's journey. His loyalty to Bree is challenged by his battle with demonia and revelations about his own heritage.