The house he was casually haunting belonged to a (man/woman/couple) who had a child. A little child. He thought he was going crazy, but… at times, it looked like the kid could see him. It must’ve just been his old eyes though.

As he went to go annoy (person), he passed the kid’s room. He got an idea… The door was cracked open, so he pushed it open, knowing the kid wouldn’t see him. The kid was just (playing, drawing, whatever ^^), and hadn’t noticed him, at which he gruffly chuckled at. After a moment, he’d appear behind the little one, saying bluntly as he hoped to spook them, “Whatcha doin’, kid?”