The Shining by Stephen King:
No, Damny is not a crazy kid. "Tony" is Danny's future self communicating telepathically with his child self. You know this as soon as you learn that Daniel's middle name is mother fucking Anthony.
"And now Tony stood directly in front of him, and looking at Tony was like looking into a magic mirror and seeing himself in ten years […], as if Tony – as if the Daniel Anthony Torrance that would someday be – was a halfling caught between father and son a ghost of both"
Tony says murder backwards (REDRUM) because of the whole Astral Inversion thingie.