There were times, more often than not actually, that he feels as though he’s seeing through someone else’s eyes or hearing their internal monologue. He theorizes that this happens when someone is removed geographically from him, but is thinking about him in some way. It is also possible that he is developing the aural illusions that accompany schizophrenia and that his internal seeing of what others are watching is actually the walls of his memory degrading, allowing past events to take precedence over present experience.
His glass was empty though so further mental plumbing would have wait. Additionally, some guy in a cheap sport jacket was knocking on his door.