Those left behind
This is an idea of what I'd lie to think what happens to all the people that Sam and Dean encounter in their travels. Some people, they hardly leave an impression, others their lives are completely changed. I'll pick at least one character from each episode as I binge watch. They may or may not crossover or connect later on but as far as I know right now, each will be considered a one shot.
Anyway I hope you enjoy!
1x01 Pilot:
Amy Hein eyed the federal marshals as they left the diner. Once she had told them about the murder of Constance Welsh, they had instantly become interested. She didn't understand though. Troy was killed on Centennial sure, but ghosts? That's wasn't possible, ghosts didn't exist. All she knew was that there was something off about those guys. They didn't act like marshals, they seemed like regular people. Weird people, but normal.
Amy fingered the photo of Troy sadly, his car was found bloody and his body missing. She wondered idly if she should look up that old ghost story after all.