Update: Please post new comments in the latest HPMOR discussion thread, now in the discussion section, since this thread and its first few successors have grown unwieldy (direct links: two, three, four, five, six, seven).
As many of you already know, Eliezer Yudkowsky is writing a Harry Potter fanfic, Harry Potter and the Methods of Rationality, starring a rationalist Harry Potter with ambitions to transform the world by bringing the rationalist/scientific method to magic. But of course a more powerful Potter requires a more challenging wizarding world, and ... well, you can see for yourself how that plays out.
This thread is for discussion of anything related to the story, including insights, confusions, questions, speculation, jokes, discussion of rationality issues raised in the story, attempts at fanfic spinoffs, comments about related fanfictions, and meta-discussion about the fact that Eliezer Yudkowsky is writing Harry Potter fan-fiction (presumably as a means of raising the sanity waterline).
I'm making this a top-level post to create a centralized location for that discussion, since I'm guessing people have things to say (I know I do) and there isn't a great place to put them. fanfiction.net has a different set of users (plus no threading or karma), the main discussion here has been in an old open thread which has petered out and is already near the unwieldy size that would call for a top-level post, and we've had discussions come up in a few other places. So let's have that discussion here.
Comments here will obviously be full of spoilers, and I don't think it makes sense to rot13 the whole thread, so consider this a spoiler warning: this thread contains unrot13'd spoilers for Harry Potter and the Methods of Rationality up to the current chapter and for the original Harry Potter series. Please continue to use rot13 for spoilers to other works of fiction, or if you have insider knowledge of future chapters of Harry Potter and the Methods of Rationality.
A suggestion: mention at the top of your comment which chapter you're commenting on, or what chapter you're up to, so that people can understand the context of your comment even after more chapters have been posted. This can also help people avoid reading spoilers for a new chapter before they realize that there is a new chapter.
Here's my take on what actually happened in the dojo incident described in chp 19.
Voldemort went there in disguise to learn the valuable martial art. He reacted badly to losing so they put him through the ordeal he described. He went along with it because he wanted to learn the martial art. The ordeal did teach him valuable lessons about losing, and he vowed to learn to control his temper and master tactics of ingratiation and supplication to better manipulate others. But he felt angry and humiliated by it (as he expected Harry to be), and also vowed to return and fulfill his revenge fantasies. So after he mastered the martial art and left the dojo, he came back openly as the Dark Lord and killed them to live out his revenge fantasies and to prevent others from learning the skills (keep science secret). He spared one student who had befriended him (and who probably stood up for him during the ordeal, like Draco to Harry), and he had that student spread the version of the tale that he wanted told (to maximize fear while hiding some of his true powers, and to deflect attention away from the value of that martial art).
For me the most natural explanation of the dojo incident is that Quirrell/Voldemort pulled a Verbal Kint. The setup is just too similar to be accidental. If you haven't seen The Usual Suspects (you should), that means ur vzcebivfrq gur fgbel ba gur fcbg gb znxr rirelbar srne uvz naq gb uhzvyvngr Uneel. I'll be quite disappointed if Eliezer's eventual explanation isn't as good as this one.