In The Lost Hero, Leo is described by Jason to look like a "Latino Santa's elf," with curly black hair, dark brown eyes, a cheerful, elf-like face, normally with a mischievous and impish smile, and a diminutive stature with a slim and relatively scrawny build. He is said to be very short, implied to be between Piper and Hazel in stature. Leo's most notable trait is that he has a look in his eyes that makes him look not only like a troublemaker, but also like he has taken much more caffeine 