Sherlock again

I started reading Sherlock Holmes in the Adventurs of Sherlock Holmes, because my brother has that book and it was lying around. I was enjoying reading that and after some reference to A Study in Scarlett, which was the first Holmes book, I decided to read that also. I put it on hold at the library and one of the options included more than one story, when I got it it turned out to be a huge book entitled The Annotated Sherlock Holmes and the word annotated is not to be taken lightly, the actually stories are in thin collumns and the annotations are almost half of the page. It has been both informative and helpful to be able to refer to the annotations as Holmes lived over one hundred years ago and moreover in London. Helpfulness aside it was also baffeling to see references to all the theories and papers written about Holmes, Watson and their adventures; to be fair people have had roughly 100 years to stew over these and form their theories but I suppose I had no idea of the fanatical popularity of these books. These theories range from the dilution level of Holmes' cocain, to Holme's upbringing, to a secret identity of Watson's wife, etc., what's more they talk about Watson like he was a real person, I know they must have known he was fictional but in their devotion to the works they seem to have almost forgotten.
I think the closest sort of fanaticism I've seen, to these Holmes junkies, might be that of Twilight fans, or maybe Harry Potter. I don't really think either of those fall into the same category of literature though (although to be fair I have not read Twilight). I'd be quite interested in hearing anyone else's thought's on the subject.