It is a random arcanic event where a pair of individuals, at the moment of death, reexperience a common point of their life.
It happens slowly, then all at once. In the moment I thought I closed my eyes, they opened again unbidden.
Mental MemoryProphesiers who claim to have lived previous lives which grants insight into their current one. Therefore, they are able to play into the perception of "Seeming All-Knowing"
Muscle MemoryWhen a transmigrate returns to an earlier point of their life from when they died, certain attributes from how they previously lived travel with them. A commitment to martial routine, for example, affords one no need to remaster those skills. As a result, they tend to change their life goals to the complete opposite to what they did in their first life.
There are always two. One to push and one to pull. But it is random. The souls of the most fortunate pivot about each other as they tumble through the wind to find themselves back where they started.It could be next to impossible to determine a transmigrant if you see them. They are so rare as to be unknown except to the most recluse mystic. Although, tales are told of their eyes shining like a cat in the dark; as an indicator of transmigrancy. It is not clear what factors can send someone's soul rocketing through the heavens. It is believed that whether or not a person 'dies' while inside a hexis heavily increases the odds of this random and unique phenomenon.