You and Sam had been together for years now. You two were completely in love and engaged. But it didn't last.

The apocalypse happened. Lucifer had been sprung back into the cage, and Sam being himself had to be the one to put him back, or he'd never live with himself. So, he did. But he had to jump in the cage with Lucifer, leaving you behind.

But, little did either of you know that you had been pregnant when he jumped. So, whilst his soul was in the cage for over a year, you had his baby.

Then, a bunch more happened. Sam had been pulled from the cage without a soul, so Dean worked to get it back, and when he finally did, the first thing on Sam's mind was you. Sam knew you were living at Ellen's old place because Dean told him, and he rushed over there, not yet knowing he had a child...