Some while back, I had a conversation with a reader. It went on for quite a while, but I can sum it up pretty quickly:
Him: “That book is terrible. I shouldn’t have been surprised. It has a prophecy in it. Stories with prophecies in them are always horrible; they’re pretty much a sign of bad writing.”
Me: “Um, no. Really, really, no.”
If having a prophecy in a story were a sign of bad writing, Homer’s Illiad and Sophocles’ Oedipus Rex would not still be read, watched, studied, and enjoyed over 2500 years after they were written. Yes, there are plenty of perfectly terrible modern fantasies that contain prophecies, but as with so many things in writing, the problem is not with the device or technique, it’s with the way the technique is employed.
What too many writers fail to realize, I think, is that from a story-structure viewpoint, a prophecy is a point of intersection between characters and plot. A plot-centered story can easily founder on a prophecy that makes the rest of the plot inevitable; a character-centered story can similarly founder on a prophecy that makes the characters’ actions appear pointless or turns them into puppets. Characters and the rest of the plot have to balance on the point of the prophecy, or the story goes lopsided and fails to work.
In most of the old Greek stories, the characters are usually struggling to avoid an unfavorable prophecy, but sometimes, they seem to see it as a deadline. Laius tries to avoid his prophesied death by disposing of his infant son (which naturally sets the prophecy in motion); Achilles, having decided to take the “die young and covered in glory” part of his prophecy rather than the “die old and unremarkable” part, seems to be cramming as much living as he can into whatever days he has. In both cases, this puts the characters in tension with the prophecy, pulling against it in some way, and that keeps things in balance.
Many modern fantasies, by contrast, have the characters struggling to fulfill a prophecy. This puts the characters and the prophecy on the same side, both pulling in the same direction. For this to work, something has to be pulling equally hard in the opposite direction, or the plot takes on an air of inevitability no matter how difficult the heroes’ tasks are.
There are several ways to make a story work anyway. One is to have an ambiguous prophecy: “If you cross the river, a great kingdom will fall.” Which kingdom? Maybe not the one you’re hoping for… Another method is to have competing prophecies, only one of which can be true, or a prophecy that predicts a confrontation, but not the outcome (or at least, not a clear outcome: “The armies of East and West will clash, and the victor will rule for a thousand years” leaves out one obvious and important fact – who the victor will be). Or have one like the one about Achilles that gives two mutually exclusive outcomes to choose between.
A prophecy that lends itself to misinterpretation, or to multiple interpretations, can provide all sorts of interesting plot twists. “The Red Dragon and the White shall battle, and at first the White shall seem victorious, but the Red shall conquer when the Boar comes out of the South” is the sort of thing that can be made either blindingly obvious or nearly impossible to interpret, depending on how the author sets things up.
What all these alternatives do is to lessen the obviousness of the “pull” of the prophecy on the plot and characters. If the prophecy says “whoso pulleth this sword from out this stone is rightwise born king of Britain,” the next step is obvious: line everybody up and have them tug on the sword. If it says “The rightful king shall be revealed under the sign of the dragon,” the next step isn’t nearly so clear…and the characters’ actions are less likely to feel scripted and inevitable.
In modern fantasy, prophecies are usually central to the story. There’s plenty of precedent for this, but it isn’t strictly necessary. It is perfectly possible to write a story set during the Trojan War that deals with the struggles of a merchant family trying to survive in a city that’s been under siege for ten years, in which none of the characters have much of anything to do with the prophecies about Achilles dying young or Paris bringing about the city’s downfall. One can also do what the Arthurian legends do: pulling the sword out of the stone is the start of the poor kid’s problems – now that he’s king, he has to chase the Saxons out of the kingdom and then figure out how to get a war-ravaged land back on its feet again, while also dealing with cutthroat court politics. Fulfilling the prophecy was the easy part.
One last key thing for any author to remember when including a prophecy in a story: the exact wording of the prophecy is the sort of thing that fans of the story will pick apart endlessly, given the slightest cause. It pays to be very careful about it, and to solicit advice and alternate interpretations from as many other people as possible, so as to catch and eliminate (or better yet, incorporate into the story) as many of the potential objections/alternatives as one can.