I'm really fussy about AUs--I'm one of those hardliners that define the term as an alternate universe that departs from a known point in canon.
A split path, a 'what-if', so to speak. So those fics that take canon characters, dump them in a whole different world with no reference to or explanation of the original canon world? Yeah, not my cup of tea. (And good god, the proliferation of these fics in the PJO fandom is scary--is the original canon really that sparse in world building? Then again, I'm sure HP had its fair share, except I avoided them pretty easily since you could easily find your own niche areas in HP fandom. I haven't quite learned to navigate PJO fandom yet.)
All this of course explains perfectly why I've spent my last couple of days 'on holiday' binge reading Percy Jackson AU fics that follow the popular fandom definition that I don't buy into. *facepalm* I blame
(Clearly just because a fic is of a particular genre/trope doesn't mean it can't be done well or enjoyable. The main issue is whether it is necessary to transplant characters out of the original world--which I would argue is why we were captivated by canon in the first place--to tell a story that uses the characters but is otherwise unrelated to canon. The obvious problem is that it's a fine line to walk without making it a completely unrecognisable piece in which the author is just telling a completely different story that happens to just reprise familiar names. How far can you go before you cross that line? I do think the fic I linked to does manage to stay just within the bounds, though. I haven't found another fic that manages to get that balance quite right, but Stucco Hearts whet my appetite for more so I feel the way I do when I binge read pulp chick lit after one decent example of it.)