Update: Discussion has moved on to a new thread.
The hiatus is over with today's publication of chapter 73, and the previous thread is approaching the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it.
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. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
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:
You do not need to rot13 anything about HP:MoR or the original Harry Potter series unless you are posting insider information from Eliezer Yudkowsky which is not supposed to be publicly available (which includes public statements by Eliezer that have been retracted).
If there is evidence for X in MOR and/or canon then it's fine to post about X without rot13, even if you also have heard privately from Eliezer that X is true. But you should not post that "Eliezer said X is true" unless you use rot13.
RE: Chapter 75.
Harry is usually rather good avoiding making reckless commitments but he seems to have thrown that caution away. I refer here, of course, to the non-interference treaty he proposed with Hermione. When it comes to things like becoming a ghost-whispering Hermione's rivals that is all well and good. That's Hermione's business. But if there is one scenario we can expect the treaty to cover - informally specified as it is - is that which prompted its very creation.
If situations such as this one are encountered in the future then Harry has lost the freedom to do what seems fundamental to Harry. Not just in regards to Hermione specifically but to anyone who has the misfortune of being in her Aura of ImPotence. He will, unless Hermione's ego happens to be sane that day, let barrages of fire and pain fall freely up that which he (supposedly) Protects.
Harry has been wondering with incomprehension how a community could endorse unjust cruelty and violence. He has self righteously condemned those who go along and do nothing. Yet now he should begin to see the temptation. He has just conceded to allow groups of ten year old girls to be beaten, permanently injured and possibly killed lest he step into the political territory claimed by an ally and with the hope that by doing so he will - in the future when they are physically capable of it - get laid! Now Harry is starting to act like a Grown Up.
I don't suggest opening with "woulda dun it anywayz" would be a particularly wise conversation move but do assert that the deal he made here would have been far more appropriate to make when Harry was interfering with Hermione, not with something more general that also included her. In this case it deserved at least a pithy one sentence disclaimer. Which is far less than the multi-point verbal contracts he has spoken up every other time he made a deal.
I would read more into it if I didn't think this was the Author forcing in a deep conversation that he thought through earlier into this situation without thinking the details through clearly. Where by 'more' I probably mean "like the above except not being flippant". It only becomes in ernest if (or when) Eliezer interjects and declares the commitment with its undisclaimed recklessness canon.
Now that you mention it, that promise does seem rather off-balance compared to Harry's usual standards.
Boring hypothesis: He's falling in love with Hermione.
Interesting hypothesis: He started out very isolated. His family wasn't abusive, but he didn't connect to anyone. Now he's having to navigate having personal connections, and it's harder for him to make abstractly good choices.