Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-24398707-20140108200752/@comment-19765459-20140108201812

Two options:

1) Jeff forgot about this. He already forgot about Peter possessing Lydia. The "You"/"Me" scene last season was only inserted because Holland pointed out that Lydia probably would not have been able to just blow off what Peter did to her, and Jeff had forgotten about it completely.

2) My personal suspicion: Deaton is manipulative and conceals things. It is implausible that a druid living in a given area would not take the time to learn the location of the nearest place of power that could be used for druidic magic. So I think that the ritual with Scott, Stiles and Allison was deliberately intended to feed power to the Nemeton, rather than doing so as a side effect. I think that Deaton used the kids for his own purposes and they are suffering weird aftereffects because he wanted to open them up to supernatural forces all along.