Mortals
Mortals, Hades knew, were fragile creatures, both in body and in mind. Even before the weather took a turn for the worse and Hadestown enticed them away with promises of riches, new shades arrived quickly, and Hermes had his hands full sorting them out.
And when the seasons began to change, they came eagerly, trusting in Hades' promises of power and food, ready to accept whatever conditions he would provide in exchange.
He was doing them a service by setting them free, thought the God of the Dead; under his eyes they were free from poverty, hunger, and the heat and cold.
Hermes said the mortals had tenacity, preserving through hardships when they could, and Hades was inclined to agree—they certainly found new and tenacious ways of boarding the train to Hadestown. Once the papers were signed they ceased to be mortals and became shades.
And if there was one thing Hades was grateful for, it was that the shades lacked the drive the mortals possessed. If they did, he thought, not even he could quell the occasional uprising.