If you assume that Quirrel is Voldemort, then either he was lying and Bellatrix was just flat-out evil, or he MADE Bellatrix the way she is and presumably his motives for breaking her out have less to do with healing her and more to do with freeing his evil minion. It's possible Riddle's body had some sort of neurological problem that made him psychotic, which Quirrel does not share, making him regret his past actions, but I think this is unlikely and that he's still just evil.
It's possible Quirrel will use Bella to perform an evil deed in the future. But breaking her out was, in itself, not evil.
The new thread, discussion 13, is here.
This is a new thread to discuss Eliezer Yudkowsky's Harry Potter and the Methods of Rationality and anything related to it. With three chapters recently the previous thread has very quickly reached 1000 comments. The latest chapter as of 25th March 2012 is Ch 80.
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: one, two, three, four, five, six, seven, eight, nine, ten, eleven.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
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: