at some point Dumbledore tells Harry that Snape is one of his most valuable allies.
I can't help suspecting that what you're actually thinking of is this:
My beloved son:
I would say that you have been so fortunate as to meet someone who enjoys the intimate confidence of our friend and valuable ally, Severus Snape.
in chapter 7, which of course was written not by Dumbledore but by Lucius Malfoy.
Snape is in a perfect position to cleave together the cleft worlds of wizardry. If he can convince Malfoy that not Dumbledore but Voldemort threatened the life of his son, he can make these old enemies into allies against voldemort.
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 93. The previous thread has passed 300 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, 17,18,19,20.
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: