A very lethargic and pessimistic member of the Leptons. He lacks the motivation and prowess to actually be effective and does not seem interested to the point that he is not phased about having mortal injuries. He quotes poetry and seems intelligent at times. While Dee Dee openly shows affection for him, Leto tries to downplay it and would rather take things slow. Leto has shown to become sad, or rather sadder than usual, when Dee Dee briefly leaves.