They did the deadwork, and sometimes he thought he really was dead. The dwarves did all the important mining work; they said that others couldn't be trusted with it--they might steal or ruin a vein or, worst of all, pass right by a motherlode and not feel it calling to them on the other side of a foot of clay. The dwarves trusted only themselves with the mining, but they needed others for the unimportant grunt work. They didn't consider it slavery. They thought it was a high honor to allow another being so close to the mines. They spoke pityingly of those who could never actually mine, giving this as a consolation prize. Did not the deadworkers get to handle the gold and gems? Did they not get to go into the dark tunnels to be reborn when they returned--

Inspiration: "deadwork" - all the mining-related work that isn't actually mining.
Story Potential: High? Maybe?
Notes: I like the idea that of course the dwarves wouldn't let others handle the mining. And there'd be a whole culture about it that would just--grind down on others.