You are Zion's experiment. Surely, you were a silent one, but there was another person in he room with you. Clearly, that person was a messed-up person. And one more person was in that room, and you can call them your friend. So Zion was walking past your door until he saw the psychopathic person stabbed a knife in your abdomen, leaving you in agony. Your friend kept you in their arms, humming a song to you that you could easily catch up to.