His appearance (his half human, half snake face) represents the term 'Two-faced'. In fiction, snakes are known to be deceptive and cunning to fulfill their own needs due to the snake in the garden of Eden. He is the first known dark side. He's also the shortest out of all the sides including Thomas. (I based this off the ticke fanfic I read called "snakes need tickles too!" From trashyswitch!)