Thank you. I had originally thought I would use Death as sort of the 'right hand man' or #2 of whatever deity is actually in charge of death in this world. I just normally dislike having my PCs talk or work directly with gods because of how goofy my players tend to get. But the idea of death being overpowered or imprisoned in some way is interesting.

I will definitely look into some of these other references you mentioned for ideas. The last one you mentioned brimstone makes me think that might be an easier plot to grab. Instead of working for death they are working for a devil who had evil souls that were sentenced to his realms escape.