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Description
Cassius is a character who appears in the 2019 CGI remake anime Knights of the Zodiac: Saint Seiya. He is a formidable warrior from the Sanctuary and serves as a rival to the protagonist, Seiya, in the competition for the sacred Pegasus Cloth.

Physically, Cassius is an imposing figure, distinguished by his large stature, muscular build, and dark skin. His typical attire consists of white pants and leather armor, reflecting his status as a trainee warrior. His personality is defined by cruelty and a willingness to use underhanded tactics, such as attacking an opponent before a match is officially sanctioned. Following his defeat at the hands of Seiya, Cassius becomes consumed by resentment and a powerful desire for revenge.

His background is rooted in six years of rigorous training at the Sanctuary under the tutelage of Shaina, the Silver Saint of Serpens. His primary motivation in the story's early arc is to win the Pegasus Bronze Cloth, a goal that pits him directly against Seiya in a decisive battle. Despite being confident in his superior physical strength and destructive power, Cassius is ultimately defeated when Seiya unleashes his cosmos and the Pegasus Ryusei Ken technique. The relationship with his master, Shaina, is portrayed as one of professional respect, with the adaptation suggesting no deeper romantic affection on his part, unlike other versions of the story.

Humiliated by his loss, Cassius finds a new patron in Vander Graad. He willingly subjects himself to experiments that transform him into a Black Saint, a dark warrior serving Graad's forces. In this new role, his motivation becomes singularly focused on vengeance against Seiya. He is assigned as an escort to Nero of Phoenix during a mission to retrieve the Gold Cloth. When he confronts Seiya again, he has learned to harness his cosmos and even developed a technique similar to his rival's, called the Onyx Ryusei Ken. However, his rage makes him reckless. During the battle, his Black Cloth begins to malfunction and overload, yet he ignores Seiya's warnings, driven mad by his need for revenge. The Black Cloth ultimately explodes, leaving him defeated.

In terms of abilities, Cassios relies initially on his immense physical strength and destructive power. After becoming a Black Saint, he demonstrates an enhanced command over his cosmos, allowing him to perform a powerful meteor punch technique of his own, the Onyx Ryusei Ken. His role in the story is that of an antagonist whose path is defined by his inability to accept defeat, leading him down a darker path as he sacrifices his principles in a failed quest for retribution. Unlike other incarnations of the character, this version does not undergo a redemptive sacrifice or express deep romantic love for his master, Shaina.