Demon Soul Ecosystem

When a being on planet Weissblatt dies, their soul is captured by demons and brought into The Underworld, where the demons feed off all the impurities collected throughout that being's life. Afterwards, the pure remainder of that being's soul is left incomplete and cast back into the world for rebirth.

If the bulk of all the being's lifelong impurities outweighs the virtues of that beings character, the soul breaks apart and it's pieces fade into the aether. If the impurities of a soul are potent enough, they may live on through contaminating an existing - or even growing into an all-new demon, seeking to corrupt the souls of living beings.

The goal of a virtuous being is to be worthless to the demons, such that your soul can enter the aether in a complete state, untouched by demonic influence.