"Bello's Diagnosis"
The black spots on Ainsley's soul were like acid, continuously gnawing on the flickering soul fire and slowly dyeing the golden-pink soul black.
The soul looked incomplete as if it was riddled with many holes.
Bello could see that there used to be something damaging nestling inside Ainsley's soul, which made this effect.
If the soul wasn't treated and Ainsley let it be for decades or so, by the time Ainsley became adults, her soul would have long been dyed black.
A black soul was dangerous for everyone because not only the soul would suddenly reject the body, the soul might also extinguish into nothingness.
Actually, the hunters who shot Ainsley's soul also didn't want to make Ainsley's soul become like this because a contaminated soul wasn't useful for them.
But they didn't mind contaminating the soul since they had a way to cleanse it before using it!