Before the modern era of copyright and intellectual property, stories were things held in common, to be passed from hand to hand and narrator to narrator. There’s a reason Virgil was never sued by the estate of Homer for borrowing Aeneas from the Iliad and spinning him off in the Aeneid. Fictional characters and worlds were shared resources. For all its radically new implications and subversions, … fanfiction also represents the swinging back of the pendulum toward that older way of thinking.
— Lev Grossman, in his forward to Fic: Why Fanfiction is Taking Over the World