On some level, we want our fictional universes to be real. We want our Hogwarts letters; we want the TARDIS to show up on our doorstep; we want to be chosen as the hero by a talking cat or to find faeries in our backyards. And creators have noticed. Many franchises have tried to play into our desire for our fantasy worlds to be real by adding a layer of meta into their creations, inextricably linking the real world and the fictional one. The key to this sort of real world tie-in is subtlety and a firm grasp on the message of the original work.