After rereading, I beleive that Mr White is Lucius Malfoy. Not only is the name an allusion to his hair, he is said to be less useful than he was in the past due to the fact that V will soon rule openly. In the past Lucius was V's puppet in the Wizengamot.
Mr Write then proceeds to sacrifice most of his magic to bind Harry Potter. I suppose with him dead, this doesn't matter.
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 116.
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.)