Born as the 13th child to Mother Leeds, a human, she cursed her baby to the devil. Turns out such a curse altered the form of her child, which killed her on birth and fled from their home after blood was shed. A resident of New Jersey for centuries, their form derives from the cells in their body, which are unstable and absorbs light much like a void. Their muscles are free-form around their skeleton, which can allow for their wings to sprout or for body parts to be larger than normal, both for cosmetic and practical use. When the cells become tougher Leeds has a sharper appearance, referred to as Frilled Leeds.

Leeds is the actual form of Tanka, both are referred to as the Jersey Devil in text.