Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-49.144.128.41-20130730142021

As I was watching this latest episode, I was just confused how did Scott and Stiles, and the others come up with the idea that Darach was someone almost killed by the Alphas. I mean, yeah later it was figured by Sheriff Stilinski, and somewhat admitted by Ms. Blake, however, before the incicent during Stiles coming clean with his Dad through chess board, this idea was already being theorized by the duo and even Cora seems to know it. How? Did I missed something from the previous episodes? 