I have this glitch in my game that I now suspect might be caused by a mod, where my Grim Reaper is replaced with a randomly generated elder. At first I thought it was just one of those random glitches in a save that had gone wonky, but it happened in a second save where I had this mod running as well. Here is my glitched Grim collecting souls of elders who passed on at work in the science career.
He showed up at the park some sim days later, without the "Soul Reaper" title, but still spewing black smoke out of his rear end, and gliding instead of walking.
I had a sim ask him what he did for a living, and the response was, in that spooky deep Grim Reaper voice, "You'll find out soon enough."
This is how "Grim" appeared in the new game I played after that one:
Don't let the sweet old lady Grim face fool you. That plea fell on deaf ears, and the poor old co-worker was reaped without a second thought.