(no subject)
The most frequent mistake in writing Alternate Universe fics, one that I see again and again, is to start with one changed element or even setting, and then to bring in more and more arbitrarily. The proper use of AU, it seems to me, is to see what would change if one element or the setting were changed; and to make it work properly, everything else should as far as possible stay the same. I think this would make the story resonate more with anyone who is familiar with the original. But to start, as I have recently seen one fanfic author do, with one of the teachers taking a youth potion in order to join Harry as a student, and then, for no connected reason, to make Ron of all people be identified as a genuine Seer, is to introduce a completely irrelevant new story element and to break the inner logic of the story. The idea of a rejuvenated teacher is a perfectly good one (given the premise that magic can do pretty much anything) and can lead to interesting and amusing situations, and, on a larger perspective, actually alter the balance of forces and redirect the whole conflict. But it must be dealt with on its own merits, not be suddenly capped with something else altogether. (To be frank, the author had already been managing it rather clumsily, showing that, having had this interesting idea, s/he did not know what to do with it. That suggests that the sudden introduction of another idea was a symptom of despair, which does not make it any better.) Every time I see this sort of thing, I get an itch to pick up the same idea and rewrite it. And frankly, I for one do not need any more plot bunnies chewing at my ankles.