When Theo first comes back to town, he says he’ll help Scott and Stiles kill The Bad Guys. Scott doesn’t like it. But he’s at the end of his rope. Innocent people are dying. He has to do something to stop it. Stiles is wary, but refuses to make Scott do this on his own. So the three of them take care of the problem. Somehow, more and more problems arise. Things spiral out of control. Theo’s seduced them not only into cold-blooded murder, but also the filthy, adrenaline fueled sex that seems to follow naturally. For Stiles, it’s just physical. He senses the danger of it all and tries to distance himself from Theo before very long. Scott is in too deep and falling fast. Love makes people blind. The Sheriff catches onto what they’ve been doing. Stiles realizes that Theo is only killing for the visceral thrill and demands that he leave Scott alone. Theo deals with things in his usual manner. By that point, Scott’s lost sight of who he used to be. The adrenaline of the hunt, of raw emotion, of Theo, is too addictive to give up.