An obsession

Dipper lost his sight in a car accent along with his leg and parents. Unfortunately his parents didn't make it and he and his sister had to live with their uncle's. Bill always liked the boy and over time when he couldn't get to see him because he had to go back home made him crazy and overly obsessed with him. Dipper got a robotic leg and his sister helps him all she can, mostly because she didn't experience what he did. She was at home with her friends when they got into the car accent. Also in this book Bill is a human well more like he looks human but have demonic powers.