The 'Killer Watch Your Back' short story might revolve around a character who is a killer. Maybe he has double - crossed some dangerous people or broken some unspoken rules in the criminal underworld. As a result, he is now in a situation where he has to be extremely cautious and watch his back all the time. There could be other characters in pursuit of him, and the story could be filled with suspense and tension as he tries to outwit his pursuers and survive.
I'm not sure since I haven't read it, but likely there is the protagonist who is in the car with the killer in the back seat. There might also be other minor characters like people the protagonist tries to reach out to for help.
In 'the killer in the back seat short story', perhaps it tells the story of an encounter with a killer in an unexpected place - the back seat. It might start with some build - up, like the character getting into the car not realizing what's about to happen. Then as the story progresses, there are tense moments as the character realizes the danger. There could be a chase or a struggle within the confined space of the car. The story may end with either the character's escape or the killer achieving their malevolent goal.
The back story of Killer Sans varies depending on different fan interpretations. Some think he was exposed to immense evil that corrupted him, while others imagine a series of tragic events that drove him to embrace violence.
One key element is the sense of despair. It's likely that he faced something that made him lose hope, which led to his violent ways. Another is the AU environment. If it was a harsh and unforgiving place, it could have pushed him to become a killer.
Jeff was a normal boy until he moved to a new neighborhood. Bullies at his new school made his life miserable. One day, after a particularly bad encounter with the bullies, Jeff snapped. He set his house on fire, killing his family. In the chaos, his face got burned and disfigured. This event drove him further into madness, and he started to kill, becoming the infamous Jeff the Killer.