The idea about playing the Gods/ Goddesses is that you put your own spin on them. Also this is taking the inspiration from Percy Jackson though is all original characters, its not directly after it but more or less a few years down the track, their all gone and things change with time don't they?

Also when it comes to creativity with the Gods/ Goddesses, I'm allowing people to play them how they wish to. If you read into the actual stories of Aphrodite you will see that she and Hephaestus actually do get a divorce after he physically catches her in his bed having sex with Ares.

As for Persephone and Hades, it depends on which version of their story you believe, from my CS it's evident that I actually believe there needs to be some love between two people to be willing to eat something that would keep you tied to a place you hate for all eternity. So that's how I play her. 

The campers don't know that they are the Goddesses at least not while they are in their human forms, it helps them to blend in while at the camp, though they do show up in their godly appearances every now and then.