My ideal Joker is a mix of a lot of what you guys are saying. Here's my sort of fan-ficky idea for how the Gotham Central show could set him up:
He should appear out of nowhere and really bring disorder to otherwise organized crime in Gotham. He starts out as Zero Year Red Hood in that sense. He is already perma-white due to albinism or just being naturally very pale but his face is never fully revealed. So you never truly see him before his Joker transformation. I imagine he has many names on the street that never quite stick: Mister Drop, The Pale Man, The Red Hood, etc. His Drop drug really shakes up the illicit drug market in Gotham, and it offers new levels of escape for the citizens and quickly becomes the hottest drug. Joker and his hooligans are the only ones dealing it, and they are mostly giving it away so nobody can compete with him at all. His goal isn't exactly to bring chaos to Gotham, but to deliver his own brand of happiness. When high on Drop you are prone to colorful hallucinations and manic fits of laughter/hysteria. Long term side effects result in muscle spasms in the face that present as uncomfortable grins. The hotness of the drug makes Joker a target of both the police and mafia families, who had long standing agreements. Eventually the cops or hired guns are able to get too Joker and torture him, trying to get him to tell them how to manufacture Drop, or some other details of the business. They torture him, whether it be scarring like a Glasgow smile, or burning him with chemicals, he scarred smile is formed. He of course just laughs it off until Batman ends up saving him, cementing the romantic aspect of their relationship in Joker's mind (Batman is truly his dark knight). Joker is now fully born as Batman removes the red hood from his head to reveal his scarred smile. Joker is imprisoned in Arkham where the movie picks up.