He is famed as a brilliant billionaire, world explorer, and eccentric scientist. Grandpa Harley’s design is a highly distinct caricature of a classic, old-school European adventurer: He features distinctively pointy black hair, prominent buck teeth, and a thick, curly black handlebar mustache. He also wears square-lensed glasses. He is almost always dressed in a stereotypical safari outfit. This includes a structured safari hat, khaki expedition clothing, and a contrasting black bowtie. Grandpa Harley can be summarized as a frantic, hyper-capable, yet remarkably detached polymath: He is described as a world-renowned explorer, naturalist, archaeologist, and big-game hunter. He possesses vast knowledge, which he used to construct a high-tech laboratory and decrypt ancient secrets regarding the game Sburb. He has an absolute obsession with big-game hunting and weaponry. His home, Half-Harley Manor, is completely packed with bizarre trophies, including taxidermied mythical beasts, suits of armor, and decrepit mummies. While he loves his family—insisting his hypothetical kids learn how to hunt and use firearms for her own protection—his intense focus on global adventures meant he was frequently absent. He leaves his hypothetical kids alone on a remote Pacific island for long stretches of time, making his parenting style highly unconventional and dangerously hands-off. He is considered a total "badass" by characters like Dave and Jade. He travels freely across dimensions, fights off massive monsters with archaic weapons, and hoards legendary relics without a shred of fear.