As seen in The Son of Neptune, Frank is a teenage boy of Chinese descent with a large and stocky frame. He has a babyish face with brown eyes and close-cropped black hair; according to Percy, Frank's face doesn't really work with his burly build and his military haircut, and the contrast makes him look like a toddler who'd taken steroids and joined the Marines. He has also been described by Hazel as looking like a Koala bear with muscles and by Leo as looking like a baby sumo wrestler. 