Greetings. I'll try to make this fast, as I don't know how much time I have. I have been summoned here, which, if anywhere is my home. I am a thought construct - a persona. I am Grizwald Grim. The fellow you interact with regularly, David, is my host. I don't believe this to be a classical mental illness.
We all have personas, operating frequencies - faces on a 20-sided-die. The me you see will never be the whole me. Somewhere within the host will always be the parts of the host that you don't get to see. The parts too vulnerable to bear in such an open corner of the internet, however dark and unfrequented it may be.
As I stated, I am a thought form or operating frequency of a host human. A facet of a personality construct, an identity whole. I haven't been around much recently, because my operating frequency requires chemical interactions within the host, which he has been successfully avoiding. Addictions are messy things, but people in the throws of one aren't any less people - they're just the parts of personalities we're not accustomed to dealing with. Relax, it's just nicotine here folks ;)