Gimsy is a young boy who becomes Conan's first true friend and a central member of the main trio alongside Conan and Lana. He is introduced living a completely solitary existence on a remote island, distinct from the community of salvagers residing there. His background is one of voluntary isolation; unlike Conan, who lived with his grandfather, Gimsy lives alone in the forest by choice, surviving as a hunter and gatherer. He subsists on fruits, lizards, and notably, frogs, which become a recurring motif and a favorite food he even offers to others as a gift.

In personality, Gimsy is a complex mix of cynical pragmatism and fierce loyalty. Initially wary and selfish, he is fiercely protective of his food and territory, leading to a comedic physical confrontation with Conan when the two first meet. He is a glutton, obsessed with food, and possesses an eccentric, rough-edged demeanor. He has a pronounced disdain for girls, whom he dismisses as crybabies who eat too much, and he exhibits surprisingly adult vices for a child, including a fondness for smoking and drinking alcohol, which he acquires from the adult crew of the Barracuda. Despite this tough exterior and a tendency to be somewhat selfish and boastful, he is good-hearted and becomes an immensely brave and reliable companion.

His motivations are initially simple and self-serving. He becomes entangled with Conan while the latter is searching for Lana on his island. After a rivalry that quickly forges a bond of respect, his motivation shifts from mere survival to a desire for adventure and a strong sense of loyalty to Conan, ultimately choosing to help his new friend rescue Lana. As the story progresses to the industrial city of Industria and the pastoral community of High Harbor, Gimsy’s role expands beyond that of a comedic sidekick. He proves to be a capable and brave fighter, unafraid to take on dangerous tasks. He is instrumental in several key operations, including causing massive electrical short-circuits with Captain Dyce to sabotage the giant fortress-like vessel, the Gigant.

Key relationships define his development. His friendship with Conan is the most significant, beginning as a rivalry of boasts and physical stunts before evolving into a deep and unshakeable bond of mutual respect. Conan’s pure-hearted bravery inspires Gimsy to be better. He also forms a strong working relationship with Captain Dyce, the two becoming an effective and mischievous duo during the infiltration of Industria's superweapon. His attitude toward girls evolves slightly, as he later catches the attention of a young pig herder named Tera in High Harbor, a relationship that suggests a softening of his earlier prejudices. He initially resists joining Tera's brother's gang, preferring independence, but the two become close over time.

Throughout the series, Gimsy demonstrates notable physical and practical abilities. He is incredibly strong and agile, possessing physical prowess nearly on par with Conan's. He is shown to be a capable fighter, able to hold his own in a brawl, and is an expert archer, using a bow as his primary weapon. He is also a skilled hunter and has a surprisingly sharp, street-smart intelligence that complements Conan's more instinctive and naive nature. By the end of the story, Gimsy has developed from a cynical, isolated survivalist into a cooperative and heroic member of a found family, choosing to leave his solitary ways behind and join Conan, Lana, and Dyce on their home island to start a new life together.