When Pretty Little Liars premiered on ABC Family in the summer of 2010, teen television had only just finished (to adopt a possibly labored metaphor) memorizing its freshman year locker combo. Critical aughts darlings like Buffy the Vampire Slayer, Freaks and Geeks, and Veronica Mars had demonstrated just how inventive and artfully edgy stories about about teens on television could be, and primetime heavy-hitters like The O.C., Gossip Girl, and Glee had proven how passionate (read: lucrative) the audiences who tuned in for those stories could become. It wasn’t until the end of Pretty Little Liars’ inaugural …