Wow, side-splittingly hilarious. But do
tell, what's a “retcon”? (English is, after
all, only my third natural language, and
I had three programming languages before
it as well…)
Author's response
Oh, that's a fair question, especially since changing a spell incantation is on the "very tiny detail" end of the range of things people mean by "retcon" -- usually it refers to something big.
A "retcon" is when some media creator goes back and says "I said this was canon, but changed my mind", retroactively changing the universe. Usually that just means any future media created in that universe will treat the new version as canon. Comic book companies do this constantly, for example.
In this case Rowling realized she goofed and had used 'ennervate' to mean its opposite, and specifically said somewhere that she was changing it to 'rennervate'. My stance on sticking to canon in this fanfic is that I have to pay attention to it somewhat in order to avoid confusing people. In this case, no one would be confused -- it's just a gesture of courtesy to Rowling which hopefully she will never know about. :)
Also, I am absolutely thrilled to have readers who are not native speakers.