In the first age, a mortal refused to accept a gift from the heavens. That refusal became a wound in reality, and from it emerged a single demon containing every unrestrained impulse. The celestial powers shattered it into seven beings, believing division would make it manageable. Instead, the fragments built kingdoms beneath the world and established a compact requiring them to compete for mortal souls.

The Underworld is a descending spiral of seven immense realms called the Seven Below. The uppermost layer is a palace of mirrors, followed by vaults of gold, gardens of forbidden beauty, a labyrinth of poisoned reflections, an endless banquet, a battlefield of living thunder, and finally a gray wasteland where all motion and memory fade. The Seven were once one primordial demon, divided by the first mortal act of disobedience. Each ruler possesses a fragment of that original being and seeks to reclaim the others.

The religion has no unified priesthood. Instead, each deity maintains a distinct hierarchy, ritual calendar, and network of temples, with the Sevenfold Synod serving as a rare forum where representatives negotiate disputes. The Synod's meetings are held in neutral sanctuaries built with seven doors, none of which may be locked. Most temples secretly honor one primary deity while acknowledging the other six as dangerous truths. Heretical reformers teach that the Seven should be reconciled, while orthodox cults insist that rivalry is necessary to prevent the primordial demon from re-forming.

The Seven are intensely involved in mortal affairs. Their cults operate as churches, secret societies, warrior lodges, merchant houses, festivals, monasteries, and criminal networks. Each deity grants miracles through dreams, omens, possessed relics, and bargains that carry literal or symbolic costs. Mortals can gain power by serving one deity, playing rival cults against one another, or attempting to reform the religion from within. Clerics, warlocks, paladins, and villains may draw on the Seven's authority, but every blessing strengthens the corresponding layer of the Underworld.

The dead descend through the Seven Below according to the debts, cravings, and wounds they carried in life. Each layer is ruled by one of the Seven, and each ruler claims the soul according to its strongest sin. The virtuous may be rescued by mortal vows, heroic intervention, or bargains with a rival deity. Souls judged beyond redemption become servants, beasts, or fuel for the layer they enter.