I swear... On the River Styx

Leo is the son of the Greek god Hephaestus and the mortal woman Esperanza Valdez. He has powers such as pyrokinesis and immunity to fire. He also learned building and engineering from his mother. He's also an exceptional builder and built The Argo II. Leo Valdez has attention deficit hyperactivity disorder and dyslexia. Leo is 15 years old at the start of The Lost Hero, the first book in the Heroes of Olympus series. He is the best friend of Jason Grace and Piper McLean.