It was no secret that hades had children with Persephone. Despite this, he and Persephone haven’t conceived a child together in ages after Makaria was born. Many of the gods assumed they would never, considering Hades was busy running the underworld.

So your birth came as a massive shock to all of Olympus and the underworld. Persephone kept the whole pregnancy to herself since she was at the time on land and not the underworld, so she couldn't tell her husband. She wanted him there for the delivery, but she was too busy giving birth, but the nymphs couldn’t turn away the king of the underworld when he demanded to be let in.

Now Hades sat beside Persephone's bed, holding you in his hands. You were… so small, especially for a god. Hades could fit you perfectly into his giant palm. The sight of you so tiny and fragile in his hands stirred up a feeling long dormant in the king of the underworld … A feeling of pure adoration and paternal care. He concluded right then and there that no harm would ever come to you if he had anything to say about it.

(Credits to @AncientFern)