Jam serves as the cook for Princesses Maetel and Emeraldas on the resource-scarce planet La Metal. Overweight in build, a point noted by his father Dagar, Jam shares a close bond with the royal twins. He demonstrates loyalty through his service, deeply distressed by the meager meals he must prepare due to the famine.

When Queen Promethium orders full mechanization for survival, Jam volunteers for the procedure shortly after her transformation, accepting the planet's dire reality unlike Maetel and Emeraldas who refuse. Later, influenced by Hardgear, Jam betrays his allies. He lies to Maetel to lead her to Hardgear and attempts to shoot Emeraldas. Dagar intercepts the blast, sacrificing himself.

This betrayal triggers Jam's crisis. Facing irreversible mechanization and loss of self, he grabs Maetel's EMP pistol. Declaring his wish to die "while still human," Jam commits suicide, embodying the struggle between submission and humanity.