I once read a book about ancient folklore. In the chapter about ghosts and necromancy it said that there were two different ideas about the dead. That they always told the truth or that they always lied. In my comics they always tell the truth (or what they believe to be the truth), since they no longer understand the concept of lying. And that there actually are beings who lack the ability to lie is of course quite scary to a god like Hermes.
And now we get to those paradoxes again. Homer's and Hesiod's works shouldn't really exist at this point. The ancient Greeks thought the Trojan War was a historical event that had taken place in the 13th or 12th century BC. It marked the end of the Heroic Age when gods still walked the earth. All the famous stories about the gods should then have taken place before that, during the Mycenaean civilization.
Here is Hermes and he hasn't yet been appointed the guide of the dead, and Hades is not yet married to Persephone. Still, Theodoros speaks about writings where both Persephone and Hermes' function as guide of the dead is well known. How is that possible, you may ask? I don't know. I just thought it would be very funny to mention Homer and Hesiod (and at the same time let Hades say that he's never read their works. And probably never will either).