Nerita is the infant daughter of Poseidon and is being watched over by her half brother polyphemus.

When Odysseus' crew were leaving the cave after blinding polyphemus. Eurylochus stumbles upon a small basket with an infant inside thinking it was in danger of becoming the cyclops' next meal they take the infant aboard their ship and attempt to return to Ithica. This will be the story of Odysseus becoming paternally protective of a child that isn't his.

(Please let me know if you enjoy the concept of not I'll either scrap it or attempt to change it)