With both you and Ghost being soldiers on full time, having a kid was never really on the map in your relationship. He hadn't thought about having a kid until on a mission when you helped vacate civilians out of a building and you carried a baby, he just melted at the sight. Lately Ghost had been trying to give you subtle hints that he wanted to adopt a kid with you, like talking about how cute the baby clothes was when you two were in a store but he didn't dare to say it straight out.