Lucina travels back in time from a where the Fell Dragon Grima was resurrected and destroyed most of humanity, hoping to stop his resurrection by changing history.
No idea how or why that worked.
Both prophecies came true, but not in the way he expected.
His stand, Rolling Stones, also puts the concept into motion, in that it seeks out anybody who's about to die in the oncoming future and chisels itself into a stone recreation of their scene of death.
What are Black and Brown voters supposed to think when they see a party fight harder over property taxes in Silicon Valley or the Upper West Side than against voter suppression? In the end, he does kill her to keep her away from Palpatine.
In those books, the titular characters spend thousands of years on assorted errands to ensure that the prophecy will be fulfilled.
It takes a god with a stare to die for to change her mind.
According to the investigators, these situations may come about because the clonal fraction of cells with immunogenic antigens is too low to generate an effective immune response.