[Well. That's curious. So he's suggesting he's not a mortal, then? But he came from the surface, and he doesn't resemble any god Zagreus is personally familiar with — to say nothing of the fact that gods typically announce precisely who they are, and why would any of them be turning into bats or heading downstairs, anyway...]

Forward...to where, exactly? Oh, gods, you're not a hero, are you? Half-god, mother a mortal, father divine, or something like that?

[Now, his shifting grows a little less idle, as he surreptitiously places himself squarely between the stranger and the passage down to Elysium.]

I'll give you credit for not harming Cerberus, but if you're heading down there to cause trouble for glory and renown or somesuch, I'm afraid I'm going to have to ask you to turn back, mate.