Hisoka first appears in the Greed Island arc having entered the game under the false name of Chrollo Lucilfer. His true purpose on the island is to find a Nen exorcist capable of removing the Judgment Chain that Kurapika placed on Chrollo's heart, as removing this curse is the only way Hisoka can finally have the fair and thrilling fight he craves against the Phantom Troupe's leader. While his past remains largely unexplored, with the character himself showing no interest in it, it is known that he joined the Phantom Troupe as a false member, donning a fake spider tattoo with the number four, with the sole intention of one day challenging Chrollo to a duel to the death.

Hisoka is defined entirely by self-serving and hedonistic impulses. He is a murderous sociopath whose sole purpose is to seek out and fight powerful opponents, experiencing what can only be described as an orgasmic thrill from near-death combat and the spilling of strong enemies' blood. He is neither purely evil nor good but rather amoral, willing to assist protagonists like Gon and Killua if doing so promises entertainment or will make them stronger for a future fight. He views promising fighters as unripe fruit, or as he calls them, green apples, and is willing to protect and nurture them until they grow into worthy opponents he can eventually destroy. This is why he repeatedly spares Gon, not out of kindness but out of a selfish desire for a more satisfying kill later. His personality is chaotic and unpredictable; he is a whimsical liar who enjoys playing cruel jokes and watching the discomfort of others, and he has no loyalty to any group, skipping Phantom Troupe meetings without concern.

During the Greed Island arc, Hisoka primarily serves as a temporary and powerful ally to Gon, Killua, and Biscuit Krueger. He agrees to join their team for the deadly dodgeball match against Razor, a formidable game master, simply because he has nothing better to do and the challenge seems interesting. His unique abilities are showcased brilliantly during this match. His primary Nen ability is Bungee Gum, which gives his aura the properties of both rubber and gum, allowing him to stretch his attacks, retract objects, and stick to surfaces. His secondary ability is Texture Surprise, which allows him to create a thin, flexible membrane of aura to change the appearance of any flat surface, effectively creating convincing forgeries. In the dodgeball game, he uses Bungee Gum to retrieve the ball, protect himself, and ultimately secure victory by sticking the ball to Razor's hands, shattering ten of his own fingers in the process. He also uses Texture Surprise to deceive Killua, altering his in-game contact list to hide the fact that he had met with other Phantom Troupe members on the island.

His key relationships in this arc remain consistent with his nature. He continues to view Gon as a fascination, praising his growth and potential. He meets Kalluto, his replacement in the Phantom Troupe, and acknowledges the young member's potential. His dynamic with Machi, a fellow Troupe member, is also present; he teases her about what would happen if he killed Chrollo, and she vows to hunt him, a threat he receives with playful excitement. Notably, Hisoka shows no significant character development within the Greed Island arc itself; he remains a static force of nature. However, his actions here are driven by a long-term development that would show its consequences later: his patient scheming to restore Chrollo. While he successfully secures the exorcist Abengane for Chrollo, this act sets the stage for their eventual, brutal confrontation, which would ultimately lead to Hisoka's death and a subsequent, darker transformation in his personality. For the duration of Greed Island, he remains the calculating, bloodthirsty magician who allies with the heroes only because it serves his own amusement and his overarching goal of fighting Chrollo at full power.