Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-24132585-20140201153705/@comment-6383956-20140211152958

I think the nogitsune possessed Stiles during "Anchors" but the whole electricity thing in "Galvanize" gave it more power or somehow jump started it. Like, prior to that, it was only controlling Stiles' mind and only at night when he was asleep -- after that, Stiles was able to do things like kill an oni.