Mybe he died, maybe he left for wherever phoenixes come from.
In canon he just flies away after Dumbledore dies, after doing a sort of lament.
Of course, Dumbledore is explicitly not dead. Though it would probably be easier to bring him back if he were (aside from issues of consent).
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 114, and also, as a special case due to the exceptionally close posting times, chapter 115.
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.)