“Jeremiah is dead! Barnabas is here! The book is wrong!”
Every time travel story has to figure out the answer to the big question, the one that Ebenezer Scrooge asks the Ghost of Christmas Yet to Come in A Christmas Carol. Confronted with a vision of a future where his own death inspires only joy and relief that he’s gone, Scrooge asks, “Are these the shadows of the things that Will be, or are they shadows of things that May be, only?”
In Scrooge’s case, the answer turns out to be things that May be. He still has the opportunity to wake up on Christmas morning, buy the Cratchits a turkey, and change his fate.
Ray Bradbury’s seminal time travel story, “A Sound of Thunder”, adds a scary element of chaos-theory mischance — stepping on a butterfly in the prehistoric past produces subtle but devastating ripples in the present. Taking up the alternate position, Robert A. Heinlein’s story “By His Bootstraps” describes a circular timeline, where the time-traveler has to follow a path that he’s already seen his future self walk.
Every writer who tells a time travel story ends up taking a position somewhere on that continuum between “the things that Will be” and “the things that May be.”
Except for Dark Shadows, of course, which is being written at the last minute, during a hurricane, by lunatics who didn’t even realize they were writing a time travel story until it just kind of suddenly already happened.
Dark Shadows Every Day 