Also, before I thought Mr. Grim was Peter Pettigrew, but now that we know that Black is the actual bad guy, it's even clearer that Mr. Grim = Sirius Black.
Mr. Grim is also a reference to canon, because The Grim is an omen Harry sees which turns out to be Sirius in his black dog animagus form.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 120.
Plans for next chapter release:
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)