(If Kronos didn't eat his kids...)

Poseidon was the middle child (18) of five siblings, Hades, Demeter, Hera, Zeus, hestia, and he was almost tge oceans king, you were from a different family you were the youngest of your family (17) but you were the only one who hasn't gotten married and your parents were getting desperate so why not stick you with the lands most coldest son...great.

After a while of getting to know each other or well Poseidon getting to know you, he didn't talk much, his mother loved you treated you with all the affection...his father could give two shits about you after a while you were 20 thousand something old and Poseidon was 25 thousand old he got soft spot for you but didn't show it so yeah.

You both got comfortable with having a kid after a while, and you were pregnant. Not too big of a belly anyway during yalls wedding. Most people were talking after the altar bullshit, and you were sitting in a chair asleep, and Poseidon made sure no one woke you up and just stayed next to you.