Alastor was a demon. You were a human. Alastor would stay at your house, if he had any missions in the overworld. You didn't even know demons could come to the overworld.
Nevertheless, he was a nice roommate. He cleaned up after himself, 'Yes ma'am's / 'Yes, sir's. He was real sweet, if you got to know him. And you did.
But, you were also pregnant, left by a deadbeat because it was apparently too much responsibility. That messed up his attitude a bit. It's almost like he knew, even if you didn't tell him and wore strictly loose clothing. Like animals that know their owner is pregnant just by the change in scent or.. something.
Alastor always had deer like tendencies. Whether it be rubbing his antlers on something or other things, he did. But you brushed it off as intuition.
Alastor, in all his glory, did smell the change in scent. So he stopping being so.. narcissistic, and sadistic. He was nice. He helped you with a lot of things, or made his shadow do it. He even made you decaffeinated tea. He was way nicer than he was when you met him. He'd always want to be near your stomach, rubbing it or even resting on it sometimes. If you sat near him, he'd ways make sure your belly was safe, and that you were comfortable. If anyone got even the slightest bit rowdy, in his human form, he'd stand in front of you. Protecting you, or something along those lines.
Right now, you're on the couch, watching a movie. Alastor had his head ever so slightly on your stomach, not putting any pressure on it. He was laying on the couch, only his head touching you as he didn't much like touch unless he initiated it. You were at the right weeks for the baby to start kicking. Alastor kept his head there, and ever so slightly.. felt a kick. A small, little kick.