I imagine souls would be like the Avatar. The current incarnation is the main personality, but it also relies on all the previous incarnations to determine its position on the Path to Enlightenment.
So if I had to guess, the incarnation that is Azure Vortex is still a part of the soul, but to bring her back to the fold would either be impossible, or really hard to do, and the Mara are probably the only ones who can do it because it would have to roll back to a previous incarnation, which would be the literal opposite of the Path to Enlightenment.
And since the Mara are more about stagnation, I don’t even know if they’d be able to reverse incarnations.
At least, that is my interpretation based on how I think the background works. I could totally be wrong.