ok, i've been listening to "Addict" a lot recently, and since the song is kind of a reflection/story as to why angel dust is the way he is, i put my own interpretation on how the people you think are happy/some other emotion that isn't sadness, fear, or anger, are the most damaged by their past(basically any positive emotion).
with the reflection being on my own past traumas and troubles on stuff like depression, anxiety, bullies, loss, and having an ex friend who abused me. while oculus's trauma lays beyond the mortal coil, in the fact that he was murdered by a doctor, and got his revenge, and soon became known as a kind of omen of vengeance for the wronged.