This is the most ‘Science Fiction’y of these stories. Quantum entanglement, the dark matter, Bose-Einstein condensates and quantum computing all figure heavily in this story. Every character in the story is a simulated human, copied from a recently deceased mortal who’s brain had been frozen and analyzed to map every dendrite connection. All their universes are simulated within a single starship, and the fleet of all known starships is small, they should be able to identify their pursuer from its drive signature.
The whole story happens in the afterlife and the real conflict of the story is between competing versions of the afterlife. Both are fictional, one may be possible, one is probable in our future, probably sooner than I’ve timed it. There are other visions of the afterlife in many other stories. The real point is, how we tell which one is real.