On the original point, of who the Defense Professor is, I saw a great idea on Reddit - the Troll is the Defense Professor.
“Not so,” said Dumbledore. “If Voldemort has not fully mastered the wards, then the wards had to believe that some Professor’s hand was at work. Else they would have cried out at Miss Granger’s injury, and not only upon her death.”
So if you need an agent in Hogwarts to kill a student, you want the wards to think that they're a Professor.
Also, about Quirrell stealing bodies
The smile that the Auror gave had absolutely no mirth in it. “So where’s the real Quirinus Quirrell, eh? Under an Imperius in the bottom of a trunk somewhere, while you take a hair now and then for your illegal Polyjuice?”
“You are making highly questionable assumptions,” the Defense Professor said with an edged voice. “What makes you think I did not steal his body outright using incredibly Dark magic?”
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 97. The previous thread is at nearly 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, 19, 20, 21, 22, 23, 24, 25.
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: