Cassim is a pivotal character from the narrative of Balbadd, known chiefly as the adoptive brother and childhood friend of Alibaba Saluja, as well as the de facto leader of the rebellious Fog Troupe. His physical appearance is striking and memorable; he is a young man of average height with dark skin and long black hair styled in dreadlocks, often tied into a half ponytail. He typically wears worn clothing befitting his origins in the slums and is frequently seen with a cigarette, a habit that reflects his restless and embittered nature. One of the most symbolic details of his appearance is the small hoop earring he wears, a matching set with the one worn by Alibaba, signifying their past bond.

The foundation of Cassim's character is built upon a past filled with poverty and abuse. He and his younger sister, Mariam, lived in the squalid slums of Balbadd with a violent, alcoholic father. Their lives changed when Alibaba's mother, Anise, rescued them from their father's abuse and took them into her home. For a time, Cassim, his sister, and Alibaba lived as a family, creating a deep but complicated bond. After Anise's death, the young Cassim was forced to become the provider for his sister. The trajectory of his life was shattered when the king of Balbadd revealed Alibaba to be his illegitimate son and took him away to live in the palace. Feeling abandoned, Cassim remained in the slums, where his sister eventually died from illness, an event that fueled his deep-seated hatred for the royal family and the ruling class he held responsible for their suffering.

Driven by this resentment, Cassim formed the Fog Troupe, a criminal organization that opposed the corrupt Balbadd government and sought to upend the existing social order. While outwardly he could be cold and calculating, especially toward authority figures, he was also a capable and caring leader to his followers, who respected him deeply. His personality is a study in contradictions; he was manipulative and willing to betray even those closest to him, yet he showed genuine camaraderie with his friends from the slums. The core of Cassim's motivation, however, is his profound sense of inferiority towards Alibaba. He hated Alibaba not for anything the prince did, but for representing everything Cassim could never be: legitimate, privileged, and living in the light. As a result, he was fixated on defying fate, a sentiment that made him a perfect pawn for the mysterious organization Al-Thamen, which sought to spread black rukh and chaos.

Cassim's role in the story is that of a primary antagonist and a dark mirror to Alibaba during the Balbadd Arc. Upon Alibaba's return to their homeland, Cassim manipulates him into becoming the figurehead leader of the Fog Troupe, using Alibaba's royal status to further his own revolutionary goals. Their relationship is the emotional core of the arc, defined by a toxic mix of brotherly love, recurring betrayal, and rivalry. Cassim repeatedly exploits Alibaba's kindness without hesitation, yet his actions are consistently driven by a desire to stand on equal ground with the friend who once felt like a brother.

This internal conflict culminates in a final, brutal confrontation. When Alibaba refuses to kill him, a desperate Cassim stabs himself with his Dark Metal Vessel, the Kokubaku Mutou, to sacrifice his life and transform into a powerful Dark Djinn. This form granted him immense abilities, including the power to generate gravity-manipulating fog and regenerate as long as black rukh was present. This final battle was not just physical but spiritual; with the help of Aladdin, Alibaba entered Cassim's heart and confronted the pain and envy that had consumed him. In his dying moments, Cassim admitted his mistakes and his long-held secret wish to be like Alibaba, finally reconciling with his adoptive brother before his rukh (the force of a soul) became fused with Alibaba's, becoming a permanent part of his being.