Board Thread:WARNING ALL USERS False Info\Spoilers/@comment-69.125.32.234-20140201200739/@comment-19765459-20140201212830

Actually, my sense is that Peter was always evil. The flashback in "Visionary" only reinforced it for me.

My theory has long been that Peter hated and resented his older sister Talia for being the Hale family Alpha. It comes out in his tone of voice when he speaks about her. Also, he knows too much about being an Alpha, and what Alpha powers can do. It's highly unlikely he just picked it all up spontaneously when he murdered Laura. Derek certainly didn't know how to do any of this stuff when he became an Alpha.

So my suspicion is that Peter always planned to kill Talia and Laura, even back then. He was quietly studying, learning everything he could and preparing for the day when the opportunity would come for him to make his move. The fire merely screwed up his timeline, but did make it easier since Laura was less formidable than Talia.