Iggy is a small, scruffy Boston Terrier who joins the group of protagonists upon their arrival in Egypt. Initially presented as the user of a remarkably powerful Stand, he is an unwilling ally who would much rather live a life of freedom and naps than participate in a dangerous journey to defeat an enemy. Captured in New York by the Speedwagon Foundation after living as a stray and even being considered a champion among the dogs there, Iggy is brought to Egypt to assist the Joestar group, though he makes it immediately clear that he has no interest in their mission or in cooperating with them.

In terms of personality, Iggy is defined by his arrogance, selfishness, and a stubbornly independent streak. He views himself as superior to humans and other Stand users, carrying himself with a pride that refuses to fawn or show loyalty to anyone. Upon his first encounter with the group, he immediately attacks Jean Pierre Polnareff, chewing his hair and even farting in his face to assert dominance. He is lazy, messy, and deliberately gross, often taking every opportunity to slink away from danger and avoid the battles of the Joestar group. However, beneath this uncooperative and grumpy exterior lies a genuine sense of pride and a hidden moral compass. His primary motivation is simply his own survival and comfort, but he is repeatedly drawn into conflict not out of duty, but out of a deep-seated sense of self-respect and an inability to tolerate certain injustices.

Iggy plays a crucial role in the Battle in Egypt arc, acting as a reluctant but indispensable scout and combatant. After Kakyoin is severely wounded by the Stand Geb, Jotaro Kujo forcibly conscripts Iggy into the fight against the user N'Doul. Using his Stand, The Fool, to form a glider, he provides Jotaro with a way to cross open ground to reach their enemy, despite Iggy's attempts to abandon the mission midway. Following this, he largely distances himself from the group, wandering ahead to Cairo on his own. It is his enhanced senses that lead him to discover the location of DIO's mansion before anyone else. His most significant solo confrontation comes against Pet Shop, a falcon Stand user guarding the mansion. In a brutal and desperate fight, Iggy is gravely wounded but ultimately kills the bird, securing the group's entry into DIO's lair. His final and most heroic act occurs within the mansion against the vampire Stand user Vanilla Ice. After witnessing Avdol's sacrifice, Iggy, despite his broken ribs and near-fatal injuries, uses the last of his strength to save Polnareff from a fatal attack, carrying him to safety with The Fool before succumbing to his wounds.

Key relationships define Iggy's journey. His relationship with Jotaro is one of forced cooperation, beginning with Jotaro tossing him across a battlefield to use him as a distraction. Iggy responds with pranks, such as hiding chewed gum in Jotaro's hat. He shares a deep rivalry and eventual mutual respect with Polnareff. While they constantly clash and Polnareff often insults him, Iggy ultimately gives his life to save his comrade, realizing only at the end that he genuinely liked him. His fight against Pet Shop is a trial by fire, an enemy that forces him to use all his cunning and push past his desire for self-preservation to win. He has a very loose affiliation with Joseph, who acts as an intermediary, offering Iggy coffee-flavored gum to incentivize his cooperation. Throughout the arc, Iggy undergoes significant development. He begins as a purely selfish creature who only participates when forced, but his character arc transforms him into a courageous, if still grumpy, hero who makes the ultimate sacrifice for his companions.

Iggy's notable abilities derive entirely from his Stand, The Fool. This Stand is composed of sand and can manipulate it at will, making it incredibly versatile and difficult to destroy, as it can simply reform after being blown apart. Because it is made of sand, its shape is fluid and constantly changing. Iggy uses this ability to form a glider for flight, create a hardened protective dome around himself, and shape the sand into claws or constructs to attack. Notably, he can also change the appearance of The Fool to perfectly mimic other people, such as creating a sand duplicate of DIO to momentarily fool an enemy. While Iggy himself is physically unremarkable for a dog, The Fool is acknowledged as incredibly powerful, with Avdol stating that even Polnareff's Silver Chariot would have no way to defeat it. The Fool's power is largely defensive and strategic, relying on Iggy's high intelligence and clever tactics to outwit faster and more aggressive opponents rather than overpowering them directly.