Phobio is a lycanthrope member of the elite Three Beastketeers serving Carrion in the Beast Kingdom of Eurazania, bearing the epithet "Black Leopard Fang". His rugged appearance features short, spiky black hair, sharp golden cat-like eyes, a muscular build, and a distinctive tail. He wears blue armor over a sleeveless black tunic, bandages wrapping his arms, loose pants, and boots. Arrogance and aggression define his early personality. Underestimating opponents, particularly Rimuru whom he dismisses as a "lowly slime" despite sensing his power, Phobio rashly attacks Rigurd and provokes Milim Nava, resulting in humiliating defeat. This fuels deep hatred for Milim and resentment towards Rimuru. His thirst for vengeance makes him vulnerable. Manipulated by Clayman's agents Footman and Tear, he merges with the catastrophic monster Charybdis, promised power to challenge Milim. As the host, he loses control and rampages until Rimuru forcibly separates them. The ordeal shatters him physically and emotionally, leading to Carrion imprisoning him as punishment. This marks a pivotal shift. He expresses sincere remorse to Rimuru, acknowledging the consequences of his arrogance. Surviving the fusion and witnessing Rimuru shelter Eurazian refugees fosters genuine respect. He abandons his grudge against Milim, especially after Carrion steps down as Demon Lord and joins Milim's forces, making her his superior. Unwavering loyalty to Carrion, whom he idolizes, persists throughout. Among the Beastketeers, he maintains functional relationships with Albis and Suphia. A significant personal evolution occurs when he forms a romantic bond with Gobwa, an ogre serving Benimaru; their connection develops over shared experiences as "love rejects". He later collaborates with Geld to confront Footman and Tear for their betrayal. Though outmatched, this action contributes to Clayman's forces' broader defeat. Following Eurazania's integration into Milim's domain and its alliance with Tempest, Phobio participates in joint military efforts, repelling invaders like the Ten Great Saints by directly engaging one of the three Battlesages. His role evolves into that of a supporting protagonist aiding allied defense and stability.