Holdem is a significant supporting character in the story, introduced as a wolf-like beastfallen who initially appears as an adversary before revealing a much deeper connection to the central conflict. His past is that of a human man who willingly abandoned his former life, having been a noble or a knight who chose to flee his position following a scandalous affair. To completely erase his royal lineage and live in peace, he made a pact with the renowned Mooncaller Witch, Sorena, who magically transformed him into a beastfallen. This act was performed at his own request, trading his humanity for a new form to hide his identity.

His appearance is that of a werewolf or timberwolf-like creature, with an athletic and muscular build. In the anime, his fur is typically depicted as gray, though other source material describes it as white. This transformation, however, is not without consequence; Zero once punished him by magically shaving a strip of fur from his head, a mark of her authority and his past arrogance.

Holdem’s personality is defined by a notable transformation throughout the narrative. He is first portrayed as cocky, self-assured, and even somewhat perverse, carrying himself with a swagger that makes him seem like a simple antagonist. He teases others and enjoys playing pranks, such as when he challenges Mercenary to a duel or tricks him during their rescue missions. However, as his backstory is revealed, his demeanor shifts to reveal a deeply compassionate and loyal individual. His defining motivation is the unbreakable vow he made to Sorena before her execution: to become the legal guardian and protector of her granddaughter, Albus. He takes this duty with absolute seriousness, dedicating his existence to ensuring her safety, a promise he keeps even as he wrestles with his own subdued romantic feelings for her.

Within the story, Holdem serves as a vital link to the past, particularly regarding the legacy of the witches and the origins of Albus. When the main characters, Zero and Mercenary, encounter him, he initially obstructs their path but eventually becomes a crucial ally. His knowledge of Sorena and the political landscape provides the group with essential context for their quest. He acts as a mentor figure and guardian to Albus, often serving as the anchor to her more radical plans. Without him, Albus would lack both physical protection and a connection to her grandmother’s wishes.

Holdem’s key relationships are central to his development. His bond with Mercenary is particularly notable; despite their rocky start, they share the experience of being beastfallen in a world that shuns them. Holdem comes to respect Mercenary deeply, referring to him as brother. This brotherhood is forged in combat and mutual understanding of the burdens their forms carry. His relationship with Zero is more complex, rooted in a history where she humbled him, leading to a begrudging respect. His primary relationship, however, is with Albus. As her legal guardian, he is unflinchingly devoted, risking his life repeatedly to rescue her from the machinations of the church and other sorcerers.

His role evolves from a rogue element to a steadfast member of the group. Initially hiding in the shadows, he steps into the light to help Mercenary rescue Albus from execution, cementing his place as a protector rather than a hermit. By the climax, he is fighting alongside Mercenary to defend Zero and Thirteen while they perform a ritual to seal away magic, actively participating in the effort to bring peace between witches, humans, and beastfallen.

In terms of abilities, Holdem relies on his physical prowess as a beastfallen, which grants him enhanced strength, speed, and animalistic senses. He is a capable combatant, proficient with a sword, a skill that carries over from his training as a human knight. He does not rely on witchcraft, instead using his cunning and physical form to fight against those who threaten his charges. His tactical knowledge and experience as a former noble also make him a useful strategist in the field.