Since I haven't read the story, I can't say for sure. But it's likely that the killer is one of the main characters.
There could be the killer himself as a main character. Maybe there's also the person or group who is after him. For example, if it's a revenge story, the family of one of his victims could be another main character. Or if it's about a power struggle in the criminal world, another killer or a crime boss could be a main character.
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.
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.
Typically, Naruto would be one of the main characters. Since it's related to Naruto, he's likely at the center of the story. There could also be his friends like Sasuke, Sakura, Kakashi etc. depending on the direction the fanfic takes. They might play important roles in helping Naruto 'watch his back' against the threats in the story.
In 'the wife killer short story', the central characters are the husband and the wife. The husband is the one who commits the heinous act. There may be other characters as well. For example, if the story is set in a small town, there could be a nosy neighbor who might have seen something strange before the murder. Or there could be a detective who is determined to solve the case and bring the wife killer to justice. These additional characters can add more depth and complexity to the story.
In a 'secret killer short story', there might be a protagonist who could be a journalist or a private investigator. They would be driven by curiosity or a sense of justice to find out who the secret killer is. There could also be the victims, who may have some connection that the killer targets. And of course, the secret killer themselves, who would be a character with a hidden identity, perhaps living a double life, seeming normal in public but having a murderous side in private.
The main character is Jack. He is the one who takes on the giants. And of course, there are the giants themselves. They are the antagonists in the story.
In many Christmas - themed short stories, there is often a central character who is on a journey of self - discovery during the Christmas season. So in 'Back for Christmas', it could be a character who has been away from home, perhaps living in a big city. Their family members, such as a warm - hearted mother, a strict but loving father, and a mischievous younger sibling could be other main characters. And there might be a neighbor or an old acquaintance who plays an important role in the story, like providing some key advice or being part of a sub - plot that helps the main character in their journey.
Not having read the short story, it's difficult to determine the main characters. But it could be a character who has been in a war and is now coming back home, trying to return to the normal life he or she left behind. There could also be other characters around this person, like family members or old friends, who play important roles in their journey back to normal. For example, a mother who is trying to help her son readjust to civilian life after military service, and their relationship could be a central part of the story.
Since I'm not familiar with this short story, I can't say for sure who the main characters are. But they could be ordinary people like a traveler, a local from Hull, or someone with a special task or goal related to Hull.
I don't know as I haven't read it. It could be a single protagonist on a solo journey back, or there might be a group of characters traveling together for different reasons.