It's a good question. As a perfect or near-perfect Occlumens, Harry could have come up with any story he wanted, if all he was trying to do was conceal certain facts (like partial transfiguration, what he really did to Voldemort, and the fact that he probably killed Lucius).
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 116.
There is 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.)