Birth of a Goddess
Disclaimer: Don't own any of the characters save Erica and her children. HP, Percy Jackson and the X-men belong to their creators, the Gods of Fiction.
In the Universe there is one thing, one being more powerful then the Gods. That being is the Phoenix. An entity of unimaginable power that can destroy galaxies, alter realities and control time. The Phoenix was created by Chaos, the creator of the cosmos, of Gaia and of so much more. The Phoenix was Chaos's first creation and some believe It's most favored. For the Phoenix was by far the most powerful and by far the most invulnerable.
Over the eons the Phoenix had chosen to explore the cosmos, uninterested in Earth. Until a woman caught It's attention and It joined with her, becoming her. She was Jean Grey. Together they returned to Earth and once there the Gods noticed the Phoenix's presence and came to investigate. The moment they were in the same room Gaia and Nyx arrived and they caused
the Phoenix/Jean, Zeus, Poseidon, Hades and Nyx came together. Merging together completely while having sex. Thus creating a child of all of them.
Nine months swiftly past and then Phoenix/Jean gave birth to Erica Nicole Phoenix Grey-Olympian. Shortly after the Phoenix left Jean's body and returned to the cosmos. While the Gods were busy realizing what Erica was. Mostly Godly, a little mortal and a lot cosmic entity. Needless to say very powerful. Unsure if she could handle being on Earth she was decided she
would be raised on Olympus. Meanwhile Jean was trying desperately to get her child back. The
X-men were trying to help her, even Scott though he was having issues with her being with another. Sure he had been with Maddie but she had been Jean's clone. Regardless Jean wasn't about to lose her daughter even to the Gods.
The Gods on the other hand weren't about to allow a mere mortal to tell them what to do with their child. Ares and Athena were all for killing her, very protective of their new sibling. As were the other Gods, no one would be allowed to take her from them. And when Jean stormed the Empire State Building with the X-men, she was greeted by all the Gods. All of whom were very angry and ready to kill them all. The audacity of them daring to attack the home of the Gods. Jean may have been host of the Phoenix and mother of Erica but that gave her no rights to anything on Olympus unless the Gods gave it to her.
Which they most certainly wouldn't as they really didn't like her. The Gods were about to blast them all when the Fates appeared.
They spoke as one:'The Child shall be raised on Olympus or all shall fall, the Child must experience mortal ways or she shall fall. For she is the Goddess of Destiny, Peace, Redemption, Time, Evolution and Judgment.She must be both Godly and Mortal to be able to judge what is right or wrong. So allow the mortal time with her child or all shall suffer.'
So, with reluctance, Jean was allowed time with her child every day, an hour that neither the Gods liked or the mortals. Jean wanted her daughter for all time, even thought about taking her and running. Until Ares told her that not only was there no spot in the universe she could hide from them, if she tried she would die. Charles Xavier managed to talk her into agreeing. As he was well aware there was nothing they could do against the Gods. So she accepted it.
And so Erica grew up on Olympus and visited Earth daily, mostly the Institute but also the camp.