They don't need to assume he actually went to Azkaban, just that he was involved somehow.
One of them mentioned "the obvious choice as to who was pulling Harry's strings." I'm not sure whether that's intended to be Quirrel or not.
I took it as a Quirrel reference. Who else (besides Voldemort) does any of Severus, Dumbledore, or McGonagall think has manipulated Harry in the past?
- This thread has run its course. You will find newer threads in the discussion section.
Another discussion thread - the fourth - has reached the (arbitrary?) 500 comments threshold, so it's time for a new thread for Eliezer Yudkowsky's widely-praised Harry Potter fanfic.
Most of the paratext and fan-made resources are listed on Mr. LessWrong's author page. There is also AdeleneDawner's collection of most of the previously-published Author's Notes.
Older threads: one, two, three, four. By tag.
Newer threads are in the Discussion section, starting from Part 6.
Spoiler policy as suggested by Unnamed and approved by Eliezer, me, and at least three other upmodders:
It would also be quite sensible and welcome to continue the practice of declaring at the top of your post which chapters you are about to discuss, especially for newly-published ones, so that people who haven't yet seen them can stop reading in time.