I'm not sure how good McGonagall's model of Harry is, so maybe you're right, and she didn't figure out what he was planning.
Hm. In my model of the wizard world, what McGonagall did was a totally obvious solution to every wizard in the room except Harry; everyone in the room not on Malfoy's side probably even came in expecting Lucius to extract this fealty vow or something similar from Hermione before Azkaban was mentioned-- it should have been fresh in their minds.
"...The girl is no part of House Potter..."
So I kinda feel like Lucius must have picked up the idiot ball to utter this. I can't explain why he didn't think of the obvious counter (was he so fixated on Azkaban that the fealty thing never occurred to him this whole time?). Unless he was trying to get Hermione joined to House Potter, but that seems really unlikely. Perhaps he didn't think there was any way he could lose to an 11 year old and thus didn't try hard enough.
I assumed the vow was obscure, ancient, Almost Never Done in modern times for good reasons (consider the content!), and that Lucius just wouldn't have imagined his model of Harry doing that with a mudblood girl.
Would've been fun to see Lucius's expression if Harry had actually proposed marriage, but that wouldn't have fit quite as well.
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 81, which should be published later today. The previous thread passed 400 comments as of the time of this writing, so it will pass 500 comments soon after the next chapter is posted, if not before. I suggest refraining from commenting here until chapter 81 is posted; comment in the 12th thread until you read chapter 81. After chapter 81 is posted, I suggest all discussion of previous guesses be kept here, with links to comments in the previous thread.
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.) When posted, chapter 81 should appear here.
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: one, two, three, four, five, six, seven, eight,nine, ten, eleven, twelve.
As a reminder, it’s often useful to start your comment by indicating which chapter you are commenting on.
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: