Slim functions as a key henchman for Lord Zero, invariably working in tandem with his partner Slam. Physically larger than Slam, he establishes a visual and dimensional contrast within their duo. Despite limited intelligence, Slim recognizes Lord Zero's frequent poor temper and the potential superiority of direct treasure grabs over convoluted schemes. Yet unwavering loyalty anchors him to Lord Zero, suppressing any impulse toward betrayal or independent action.

He routinely shoulders strenuous physical tasks for his master, encompassing manual labor or direct combat. When missions unravel—often due to errors by Slim, Slam, or Dr. Nitro—Slim typically absorbs blame and weathers Lord Zero's fury. This recurring cycle of failure and reprimand persists across their exploits, though Slim's dedication never falters.

Official media consistently depicts Slim without evolution in backstory, motivations, or narrative purpose. He operates strictly within Lord Zero's established hierarchy, advancing the protagonists' challenges through his subordinate role.