Harry Potter and the cryptographic key
Status
Summary
This is designed to start after chapter 102 of Eliezer Yudkowsky's "Harry Potter and the methods of rationality" (google hpmor). It was written by a fan waiting impatiently (but constructively) for the story to be finished. Read it before this. As usual, characters are owned by Rowling or Yudkowsky. Update: added vignette at end.