Blood stars are actually UFOs!
That's actually not too far from what would be the true physics/mechanics behind the Bloodstars: three objects in geosynchronous orbit. That would give you the three objects in the sky that are always in the same position, and do not move with the regular stars and planets.
In Anne McCaffrey's Pern novels, the three colony ships that took the colonists to Pern were left in geosynchronous orbit. When the colony devolved into a medieval lifestyle and forgot about their technological origins, they forgot about the colony ships. The three stars visible in the sky became known as the Dawn Sisters, since that is when they were visible in the reflected sunlight. In a different part of the world they were seen at dusk and were known by another name (which I can't recall right now...).
