I know exactly what you mean! Sometimes associated with the literary concept of "death of the author". I myself tend to pick and choose which of JKR's post-DH "apocryphal" revelations I accept into my own head-canon. I suppose we could start talking about fandom in terms of sects and denominations, if we're feeling geeky enough.

As for Bible!slash, I recommend a bit of David/Jonathan, because, well, it's practically canon anyway.

ETA: http://www.fanfiction.net/book/Bible/