Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-69.125.32.234-20140204062759/@comment-24421944-20140205025214

Finstock wrote: I think that the whole "Claudia was also possessed" thing is a red herring. Judging by Melissa's reaction to reading the file, I'm gonna guess there was something we didn't see, some hereditary disease that she's also afraid Stiles has, (unaware that he's actually possessed by Void).

That would definitely fall into the 'trickster' area of the nogitsune, tricking Stiles into thinking he is mentally unstable when he really is not.