I will call it... The Odyssey!
-xXHomerfangboi420yoloxX445
I'm not gonna say that you didn't blow my mind.
But as far as I know none of those stories actually featured before that one.
IMHO, retelling a story (like someone rereleasing the translation of little red riding hood) isn't fanfic, and adapting mythology (like Dresden or Atticus) isn't fanfic.
But something like 'Odysseus goes shopping' is fanfic.
Artistic integrity is hard and any new universe is inevitably going to be a cobbling-together of other universes... But guess what, that's not plageurism. Most assignments are cobblings-together of other peer-reviewed literature, and you Even Have to Show That It Is. Mithril happens everywhere even though Tolkien had it first.
The Scandinavians had the svartalves before we had the dwarves, and even still we've been slowly borrowing more and more from stereotypes to refine them into the short rugged mead-guzzlers we have today (as a MASSIVE counterpoint to the original svartalves).
Point being, that's not actively copying the characters and setting from another person's work. Hell, even forgotten realms and baldur's gate books which all have the exact same (DnD) universe feature completely new and complex characters every time.
I would also NOT consider 'Every story written in the real world' as a fanfic, or a 'borrowed universe'. That's dumb.
Seeing as the greeks considered their real world to be constantly full of the bickering and petty confusions of their gods, I say it doesn't count.
Iliad, Odyssey, Aeneid, Divine Comedy ring a bell?
Divine Comedy is full of so many original ideas that even the church had trouble with it. Dante is a completely original character too.
Iliad and Odyssey are basically a biography done greek-style (Y'know, with 400% more monsters and everyone being Big Damn Heroes). As seen above, not fanfic.
Aeneid I unfortunately can't comment on, as I haven't read it.