An idea I read on the HPMoR subreddit that I don't remember finding here is that "the very stars in heaven" could refer to the Blacks (Every last one of them that we know of has star, constellation or galaxy-related names, including Draco). Hermione also offered "the skeleton is a key" as a hypothetical for what a prophecy that means "Susan Bones has to be there" might sound like, and Hermione did study prophecy on Harry's urging, and we know that Hermione retains book knowledge much better than Harry, though this is still rather weak evidence for a stars -> Blacks style riddle. It did seem pretty unlikely that Belatrix/Sirius would have a reasonable way to reenter the story in the time that remains, but that particular interpretation of the prophecy does point that way--and they are unclosed plot parentheses in the story's final stretch.
Side note: Narcissa was a Black by birth (Belatrix's sister, in fact), and "stars in heaven" is, as other readers have pointed out, an odd phrasing for what would normally be called "the heavens", but not particularly odd if heaven = happy afterlife or wireheading.
The word "very" in this sense means "literal". The prophecy is talking about actual stars.
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 90. The previous thread has passed 750 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.
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: