There's a rather flat look from Idia as she speaks, a pause, then answering, "I can't imagine a worse torture than having to live for so long. It must be hell. I mean, you know, assuming you were human, which you're clearly not, so I have no clue what kind of mental state you have." Really, how does anyone stay sane for that long, assuming she is even that.

Also, this just opens up a whole bunch of questions. Sure, they may not really interact around the train, but lets face it, the name 'Death' really does stand out, even if just hearing her talk to others or others talking about her. And he doesn't mind Thanatos, and Mort, but also, Idia easily accepts that he's a god. So Death? Goddess? Or just the concept of death manifested into a physical form? Sure, whatever.

"And fun is a luxury not all get."