In a sneak peek video for Teen Wolf Season 3, Episode 8, "Visionary," we get a whole new view of Derek (Tyler Hoechlin). His sister Cora remembers him quite differently from the moody Alpha we know and love. What changed him? A girl. (So... not losing his entire family in a fire. Good to know.) "One minute you're in this blissful teen romance, the next there's just fangs, glowing eyes, claws." This episode will have a ton of flashbacks, so we'll see not only Derek but some of the Alpha pack many years ago.