Actually it’s a surprisingly interesting question…
Who Killed Albus Dumbledore? – Edited by John Granger, published in 2006
First off, let’s take a moment to enjoy a really excellent word, which gets invented in the introduction to this book:
Interlibrum – the period of time between the publication of two books. I love this word.
This is the first of a stack of no less than five books written or edited by John Granger that I, mostly accidentally, read all in a row. Unlike the rest of them, which are more typical literary criticism this is a series of essays speculating on the events of Deathly Hallows by a group of fans. Its actually adapted from discussions that occurred online at the time.
So this is, just as much as it’s a book of criticism, a crystalized piece of Harry Potter Fandom of Yore. And it’s a bit of fandom at its best. The last bit of Book Seven speculation, from Mapping the World of the Sorcerers Apprentice was deeply boring when I read it post-Hallows, but this was definitely not. Even reading it as someone who had just finished rereading Deathly Hallows the theories being put forward were interesting, and plausible, and well researched. They were all based on thorough and creative analysis of the first six books, and even when I knew they weren’t actually true, they were convincing. And being convinced by them was fun.
The real strength of a good fandom, is that where the canonical work is the work of a single bright and creative author, or artistic team, writing from a single perspective, fandom is full of a huge number of bright and creative people writing from a multitude of perspectives, and that definitely shows up here.
The theory that Remus’ strange behaviour was a sign he was being impersonated by Peter Pettigrew was probably more interesting than the actual story. There were two totally different and equally fascinating takes on Slughorn (+ the third that actually showed up in Deathly Hallows). The implications of having three world-class potions masters (Snape, Slughorn and Dumbledore) in the same school at the same time were another highlight I would have enjoyed seeing more of, either in the actual books or in fanfic. If anyone has recommendations, the comments are open.