I cannot tell you enough how many times "I hear voices" really means "they're my own thoughts" because of ignorance of the difference.
Reading the description, he seemed like an antisocial in the making. The fact that he hid the gun afterward and bought the headset anyway is not something a psychopath would have the presence of mind to do if they were that sick. They would be too disorganized.
He shouldn't be tried as an adult but he needs some fucking treatment.
XI Wiki



