Fantasy
A prophecy works best when it is slightly suspect.
If it behaves like a law of nature, the story can start to feel pre-decided. If it is just a story people keep repeating, then the more interesting question is who gains by calling uncertainty fate. That usually tells you more about the world than the prophecy itself.
Fantasy gets stronger, to me, when prophecy is treated as an instrument as much as a truth. Not because the future is fixed, but because someone is always trying to make it look that way.
If it behaves like a law of nature, the story can start to feel pre-decided. If it is just a story people keep repeating, then the more interesting question is who gains by calling uncertainty fate. That usually tells you more about the world than the prophecy itself.
Fantasy gets stronger, to me, when prophecy is treated as an instrument as much as a truth. Not because the future is fixed, but because someone is always trying to make it look that way.