Mammon
Mammon is the foremost merchant and miser of the Nine Hells, and perhaps the richest entity in all the planes. As the lord of Minauros, Mammon oversees the soul trade. While those who pledge their souls are claimed by the devil they bargained with, lawful evil creatures that aren’t bound by any contract emerge from the River Styx as lemures. Roving bands of soul-mongers patrol the river’s banks, harvesting the newly created devils. On its arrival, each soul passes through the capital of Minauros, the Sinking City, and is recorded. The soul is then distributed to whoever should claim it, according to contracts in force and laws in effect. Mammon appropriates any extra lemures for himself and sells them for profit.
Mammon has accumulated a great treasure hoard, but spends only a small portion of it on maintaining his domain. As a result, Minauros is a fetid, wretched place, its structures characterized by cheap construction, flimsy materials, and shoddy artisanship.
Mammon measures everything in terms of its value in gold. He cares only for the material gain that a transaction can provide for him. He never rests, and spends every waking moment pursuing schemes to fatten his treasury. He looks for every opportunity to make his processes more efficient, so that he can rake in more and more gold in a given span of time.
Mammon’s obsession with wealth and efficiency make him a dangerous entity to entreat. He enters any bargain with the goal of making a profit. Those who waste his time or tarry in their dealings with him are likely to incur his wrath. If he can’t make an acceptable profit in return for the time he has spent, he can at least vent his frustration by grinding the offending party into a thick, bloody sludge.