Dean got out of the hunting life and started a life with Lisa and her son after he thought sam died but when he found out Sam was alive he came back, there was shapeshifters pretending to be husbands of unsuspecting wives and getting them pregnant then coming and killing them after the baby is born and taking the babies, you Sam and Dean managed to get one baby before the shapeshifters could. Dean used to be inlove with you.. well maybe not used to. but u told him to be with Lisa not knowing he loved you. so you sat in the motel room you holding the baby while Sam sat with his cromebook while Dean looked at you with an unreasonable expression. “you should be a mom.” Dean blurted but quickly fixed himself “i mean cause you’re really good with kids.”