Hendricksen is a character from the narrative who stands at the center of a major conflict within the kingdom of Liones. In terms of background, he is one of the two former Great Holy Knights of the realm, sharing the title with his lifelong comrade, Dreyfus. He is a direct descendant of the Druids, a reclusive clan of forest sages from the land of Istar. This heritage grants him knowledge of ancient and forbidden magical arts that are distinct from standard Holy Knight practices. His childhood within the Druid community was deeply scarring; he was assigned the grim task of guarding corpses in a graveyard, a duty that instilled in him a profound fear of death and the darkness. Because his natural magical ability was considered cursed by his village, he was eventually driven out, which led him to Liones to become a Holy Knight.

In terms of personality, Hendricksen is characterized by a calm, calculating, and thoughtful demeanor. He rarely loses his composure and is known for his logical and analytical approach to situations. While he appears cold and sinister for a significant portion of the story, this is later revealed to be a corruption of his original, gentler nature. Before falling under external influence, he was known to be bright, sociable, kind, and patient. After being freed from this corruption, his true personality re-emerges, revealing a somewhat naive, absent-minded individual who is deeply remorseful for his past actions. He suffers from a lingering fear of darkness due to his childhood experiences and can be socially awkward, sometimes taking things too literally or making unintentional errors in judgment. Despite his formidable power, he is a dedicated healer and apothecary who values kindness above all else, even if it was once mistaken for weakness.

His primary motivation evolves drastically over the course of the plot. Initially, Hendricksen appears driven by a destructive ideology, believing that Holy Knights cannot exist without war. To give their lives meaning and to instigate a second Holy War, he seeks to resurrect the Demon Clan. However, it is eventually revealed that his actions were not entirely his own. A decade before the main story, an expedition to the ruins of Danafor led to him and Dreyfus being manipulated by a demon named Fraudrin. Under this insidious control, Hendricksen was coerced into poisoning the beloved Great Holy Knight, Zaratras, and framing the Seven Deadly Sins for the crime. His subsequent experiments with Demon blood and his coup against the kingdom were all steps orchestrated by Fraudrin to break the seal on the Ten Commandments. After the seal is broken and the demonic influence over him is purged, his motivation shifts entirely to atonement. He dedicates himself to rectifying his wrongs, protecting the kingdom, and saving his friend Dreyfus from Fraudrin's possession.

His role in the story is that of a central antagonist in the first major arc, later transitioning into a repentant ally. As the Great Holy Knight, he seizes control of Liones, imprisons the king, and uses the blood of a Red Demon to create a new generation of powerful but corrupted Holy Knights. He serves as the primary obstacle that forces Princess Elizabeth to seek out the Seven Deadly Sins. After being defeated by the Sins, he is kept alive by Dreyfus and is forced to complete the ritual that unseals the Ten Commandments, inadvertently freeing himself from Fraudrin's control in the process. Thereafter, he becomes a supporting character, using his vast knowledge of demons and druidic magic to aid the Seven Deadly Sins in fighting the very forces he helped release. In the aftermath of the final war, he fully retires from being a Holy Knight and dedicates his life to operating a medical clinic or apothecary in Liones, a role he continues to hold years later.

Key relationships are central to his character arc. His bond with Dreyfus is the most significant; they are childhood friends, rivals, and fellow Holy Knights who were both victims of Fraudrin's manipulation. Their friendship is severely strained by Hendricksen's actions, but his ultimate goal becomes to liberate and reconcile with him. He holds immense respect for the slain Great Holy Knight Zaratras, whose death he was manipulated into causing, a source of great personal guilt. He develops a deep respect for Meliodas, the captain of the Seven Deadly Sins, both as a formidable opponent and as an ally. He also has a complex relationship with Gilthunder, a young Holy Knight who served him while corrupted but later fought alongside him against a Gray Demon after the truth was revealed.

Hendricksen undergoes a profound development, moving from a villain to a redeemed figure. He starts as the mastermind of a coup, a symbol of tyranny and dangerous ambition. After his defeat and the severing of Fraudrin's control, he is confronted with the horror of his crimes, which he does not remember committing. This leads to a deep and genuine desire for penance, not forgiveness. He transitions from experimenting with demonic power to using his skills to heal and protect, fighting alongside those he once sought to destroy. His final development sees him completely abandon the path of a warrior for that of a healer, finding peace not in grand battles but in the quiet service of running a pharmacy and tending to the sick.

In terms of notable abilities, Hendricksen is a highly powerful and versatile combatant. His natural magical power is called Acid or Corrosion. This ability allows him to generate a substance that can rapidly dissolve, rot, or wither anything it touches, making it extremely lethal. He can also use a secret druidic technique known as Purge, which is capable of exorcising unnatural souls or entities, such as separating a possessing demon from its host. Another druidic art he possesses is a forbidden form of necromancy that can temporarily reanimate the dead, though repeated use degrades the soul. Seeking greater power, Hendricksen experimented with demonic blood for ten years. He first injected himself with the blood of a Red Demon, granting him enhanced strength, regeneration, and the ability to wield Hellblaze, a black, inextinguishable demonic fire. He later injected himself with the blood of a superior Gray Demon, which transformed his body even further, granting him horns, wings, an even greater healing factor, and access to powerful techniques like a dark energy storm. After the Ten Commandments are unsealed, he loses these demonic powers but retains his original Acid magic and druidic spells, which he continues to use as a support fighter and healer.