It's also possible/likely that the Malfoy household is either involved, or believes that one of their allies is involved, in a revenge killing.
It could be House Malfoy and Friends, but if so, we would still need some reason why Quirrell would not have told McGonagall that the troll was likely after Hermione. If Quirrell did want Hermione dead, he would most likely have kept any other potential murderers away from her so that her death could occur at a time and in a manner that would suit him best. So the most probable explanation is that it was, in fact, Quirrell.
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 88-89. The previous thread has passed 500 comments.
There is now 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.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: