Even when i was pretty far gone, I rather knew I was hallucinating, partly because the hallucination introduced himself as the "other guy who lives in the head, thought I'd come out and explain a few things". Was wearing a ski mask and sat down on the edge of the bed and after removing the blasted t thing began to shame facedly apologize for making such a mess of handling my grandfather's death when i was a kid.., I mean I felt the bed sag under his weight! I told him he was an halluination and he told me "whisht! I'm an animus now enough with that where was I?" Only thing I met talked more than I do! That's when I knew my meds were not working.
Since then I learned in therapy I probably also have some sort of dissociative disorder that includes depersonalization in crisis situations and some "shifting" that this Character was alluding to. Not a true alter, but not far from it.
Don't know if this is part of the Bipolar thing or if it is a result of some of things that have happened to me because of the bipolar stuff, the recklessness, bad judgement, etc. ie trauma related.