When Demeter was younger she had been a romantic at heart who longed for her own happy ending. After the 'Titan War' she thought she might have found it in Zeus. He was strong, handsome and charming and she fell as soon as she met him. When the brothers drew lots, she assumed Zeus would make her his Queen and they would live happily ever after with their own little family. She was not expecting him to cheat on her with Hera as soon as he was left alone.
Nobody had known that Demeter and Zeus had been together until after Hera forced him to marry her. Demeter was ashamed and heartbroken and fled Olympus for the human world. She was given the Earth to repay the pain that had been thrust upon her. Zeus was given the sky and was proclaimed as King of Olympus and made Hera his Queen. Poseidon was given the oceans and was entitled Master of the Seas and eventually made Amphitrite his Queen. The eldest brother, Hades, was left with the underworld and made Lord of the Dead. As far as Demeter knew Hades never took on a wife or an official consort. She didn't go up to Olympus very often so she had missed a lot over the years.
Not long after she is made Goddess of Agriculture among many other things, she discovers she is with child. She refuses to let Zeus steal her child away or try to tell her how to raise her. Zeus only agrees only because Hera forces him too. He says for now she is yours but not forever. Demeter assumes he is threatening to take her child away in the future. He only asks that when she is born she be brought up to Olympus for a proper christening as the first child born during peaceful times. The way he phrases it makes it impossible to refuse.
Her daughter is born on March 20 and she brings her up to Olympus as agreed. She didn't expect that Zeus would care all that much about her name or her status. She had already found the perfect name for her little miracle. She was announced and she walked in to discover that all of the Olympians were present. She allows Zeus to hold her so he can present their child to the others. She tries to keep an eye on her little girl at all times, but there are too many people trying to get her attention and congratulate her.
When she finally makes it back over to Zeus and her little angel she can't decide if she is shocked more by what she hears or who is talking. She freezes as she takes in the sight before her eyes. Zeus is presenting the baby just like she had left him. She doesn't expect for Hades to be there. He is not known for being social or coming up to Olympus.
Zeus says, "She is to be called Persephone as the fates have predicted."
Hades looks down at the newborn and watches her open her eyes. "Destroyer of Light"
Demeter quickly rushes over to the two men and snatches her child back who immediately starts crying as she yells, "No way in Tartarus are you naming my child that horrid name. She is to be called Kore." The two men step closer at the newborn's cry. "Now look what you have done, you upset my Kore."
Hades glances down at the weeping child and then back at the women hugging her too tight. "You have no power over fate little sister, be sure to remember that." When he steps closer she freezes in fear not sure what he plans to do. When she sees him reach out for her Kore, she tries to take a step back protectively but Zeus restrains her with a hand. The room has since fallen into a hush and wonders what is going to happen. Hades runs a single finger down her baby's cheek. The little one stops crying and peeks up curiously at the new person touching her. "Goodbye Persephone." He disappears in a swirl of smoke.