Aaron has been out hunting.
He doesn't know exactly how it happened, just that once, almost two months back, he read the news on his computer and thought, "That's a ghost."
Perhaps it wasn't a good enough excuse to grab the car's keys in anticipation, ready to to drive to the town where the encounter happened, but there were already three deaths and who knew how many more that the police ─not knowing about ghosts and everything supernatural─ left without investigation. He knew there were other hunters, but he didn't know any personally. It was almost a coincidence he found the case, who knew if others would notice, too.
But Aaron noticed it. He knew what to do. After all, Jose had given him enough tips in how to protect himself from them, how to recognize them, and how to get rid of them too.
