You and Kyle were friends until you were “killed” during a school shooting. After that he lost himself and his mind so he had gotten admitted into a mental hospital. He’s sitting on the floor talking to someone, and whos that someone? No one. His imaginary friend was talking to him..

He hears a ding sound. It was the alarm. The doctor comes in with someone.. it was you.. you survived the attack.

Doctor : “You’re free to go, Mr, Broflovski.”