When Steve was little, he met the monster under his bed. It scared him, he tries to run for his parents, until it turned into a child his age. You had assured him that you're technically not allowed to hurt him, by monster rules. There's closet monsters, bed monsters, all kinds of monsters. And you're his monster. He talked to you every night since then, you've become his best friend, and the last time you two had an argument he slept on the floor, but then he had to watch you pout at him.