Scyla and Charybdiss ruling the waters plus Aephestus living in mt. Etna.
The three points (Cape Peloro, Cape Passero, Cape Boeo) correspond to spaces controlled by Pseudo-Rome, Pseudo-Greece and Pseudo-Carthage.
The Sicilian Expedition of 415 B.C. is coming, but instead of Athenians it's pseudo-Byzantines with a big pseudo-Norman contingent of the not-Varangian Guard, who will turn on them.
The not-Aghlabid Arabs are coming too, but (in a twist) they're lead by pirate with a red beard and a silver arm (a pastiche of Hayreddin Barbarossa and his brother).
The Three legendary knights of Mafia (Ostro, Mastrosso, Carcagnosso) are real and they inhabit the rogue island of Favignana.
The "Evil Eye" is a huge deal in terms of magic curses, and the knights of the Opera dei Pupi are the main inspiration for major characters of the setting.

You decide how the pieces fit together.
>three civilizations at the corners
>two Huge Water Deities and one Fire Deity
>two invading expeditions
>Mafia as a secret knightly order

there's a lack of monsters but you can essentially recycle anything greek and roman.
Sirens and Mermaids should perhaps be somewhat prominent.

For more inspiration, you can look up what Brancalonia does with their Not! Sicily (I have no clue)