The Creator had created Impthus out of the very essence of light itself. And so do all of his fellow followers. The Athlran glow endlessly, no matter where they are. They have a pair of white wings and their form radiates bright light, as the High Heaven itself.
At the beginning of life, before the Living World was created, the Creator had created only Felenthur and Impthus, that he made them both as brothers. One with the heart of darkness and one with the heart of light. Impthus was given the High Heaven with the Orb of Light. While, Felenthur was given the scorching plains, where soon, he transformed the plains into the Burning Hell as soon as he managed to made a plea to the Creator. A plea which he asked to create an ally for him. Thus, the Demon Princess and Princesses were born into the Burning Hell.
They have no souls, but they live. They are formless, but they walked. They are unseen, but they reveals. They walk the dark plains, but they show the lights. And they were given a chance to choose side. And yet, they chose righteous. And that's the Farons. Creature that walks the void realm.
The secret for immortality has been discovered by an eccentric wizard/mad scientist. Its found you need to reapply once a month. As people stop dying, and the birth rate increases exponentially, people are forced into homelessness, because of the need for food reamins the same, and food is not being produced fast enough to feed the undying population. The PCs have to find the creator and kill him, and destroy production, to save the world from undying, unending torture from hungryness.