Monster: Naruto Kurama merged multiple personality disorder

Neglected Naruto meets Kurama at 5 YO. He accepts to host it inside his body rather than inside the prison in exchange for learning how to speak, for gaining strength and because Kurama would stop putting him in a permanent paranoia of his own shadow and of darkness. Shadow themed horror, Sasuke traumatized, Itachi dead after the Uchiha massacre. Very dark alternate non canon story