The sound of the drumbeat echoed down the rough stone passage. The slimy stone walls were latticed with colorful looking molds that added to the pungent bouquet of earthy rotting aroma that was nauseatingly sweet. Over the drumbeat, the sound of soft flesh inching it's way over the floor, coming closer.
Into the chamber they crawled, pink fat worm things. Behind them the tormentors poked and prodded them forward with their perverted shepherd's crooks. Sharpened steel replacing the rounded wooden top.The drummer came last into the chamber. As the worms were gathered together into the pen within the circle the brethren waiting for them in the chamber were finishing the outer form of the circle.
The candles were lit, the words spoken. The brethren stood around the chamber, chanting, drumming, and thumping their crooks. And suddenly there was a man standing in the circle. No flash of light, no puff of sulfuric smoke, no ground shakes, just... there. The drumming and chanting faltered as they all looked at him.
He was dressed in rich black fabric, embroidered with black. His thin beard and short hair was well trimmed, and the only real sign of his otherworldly nature were the small tips of horns protruding from his forehead. He looked down at the worms grubbing around in the pen with him. They were making a mewling noise, and the demon's lips curled in disgust.
"Next time, you can leave them out of the circle." the demon nudges the worms away with his tooled black leather boots.
Demons trade in souls, and while they prefer living souls that are given willingly, they are also willing to accept "used" souls. Usually these are captured at the moment of death, often by curse or other magical means. Sometimes they form when the body is killed by a powerful undead. They eventually manifest as small pink worms with baby faces. Depending on how they're cared for, they can grow and develop in a variety of ways. Some like making them fat while simultaneously torturing them, twisting them into an unrecognizable abomination that's perfect to transform into a demon.