Basement

"There is no such thing as magic," Uncle Vernon had said. But there is. There's gotta be... AU/Child Abuse/Mental Abuse/Torture/Starvation/Phycological Torture/Strong Violence/Descriptive. Summer before fifth, Vernon manages to convince Harry that Hogwarts has been a fantasy invented by him, as an abused child seeking mental refuge from his tormentors. How? Why? What happens next?