Percy Jackson is the protagonist of The Lightning Thief. Riordan created Percy for his son as a hero who struggled with the same conditions his son did. Percy (along with the other demigods) grapples with dyslexia and ADHD, two contributing factors to his constant changing of schools. For much of the book, Percy lets these conditions define him, thinking of himself as “A dyslexic, hyperactive boy with a D+ report card” and nothing special (38). Later, Percy learns his dyslexia and ADHD directly relate to him being a demigod. Demigods struggle with written English because their brains are wired to read ancient Greek (dyslexia), and while ADHD presents a challenge at a human school, it translates to heightened senses, allowing demigods to concentrate better in battle. The trouble dyslexia and ADHD cause Percy in the human world allows monsters to find him and thus eventually leads him to Camp Half-Blood.

Percy is a son of Poseidon and a forbidden child. To prevent overly powerful offspring, Zeus, Poseidon, and Hades swore on the River Styx not to have more children, an oath with dire consequence if broken. Percy struggles with his demigod nature, even more so once he learns who his father is.