Well, Naruto is probably the central character as the title implies he has a significant role as the 'first vampire'. Other characters from the Naruto series like Sasuke or Sakura could also be important. They might be involved in Naruto's transformation into a vampire or they could be trying to help him deal with his new state. And of course, there could be some powerful vampire antagonists who play a major role in the story.
Naruto would most likely be one of the main characters. Given the title, there might also be some original vampire characters created specifically for this fanfiction.
Obviously, Naruto would be one of the main characters since it's in the title. He's the one with the 'vampire god' transformation. There might also be his friends like Sasuke and Sakura. Sasuke could be either a rival or an ally in Naruto's new vampire - related adventures. Sakura might be concerned about Naruto's change and try to help him control his new powers.
Obviously, Harry Potter would be one of the main characters. And the first vampire would be a central figure too. There might also be characters like Hermione and Ron, who could be involved in the story in different ways. For example, Hermione might be researching about vampires to help Harry understand the situation better.
In many fanfictions, there could be a human character who becomes the first vampire's nemesis. This character could be a brave warrior or a skilled hunter. There might also be some sort of elder or wise figure in the story, like an old mage who has knowledge about vampires and tries to either help or stop the first vampire.
Naruto and Shinso are the primary ones. But we could also have an old and wise vampire elder as a main character. This elder could have knowledge about a prophecy that involves Naruto and Shinso, and his actions and decisions would drive a lot of the plot as he tries to either fulfill or prevent the prophecy.
One of the main characters in early vampire stories could be the victim. In the original tales, there was often a person who was targeted by the vampire. This victim was usually an innocent, and the story revolved around their encounter with the vampiric being. Also, there were sometimes characters like the local villagers or the priest who tried to deal with the vampire threat.
Often, the main character in the first original vampire story is the vampire itself. It's the central figure that drives the horror and the plot. There might also be a victim or a potential victim who is trying to escape the vampire's clutches.
The main characters in the first vampire story are likely to include the vampire itself. It could be a person who has made a pact with the devil or been cursed in some way. Then there are the victims, who are usually unaware of the danger until it's too late. And there might be a character who discovers the truth about the vampire, like a doctor or a scholar, and decides to take action against it.
I'm not sure specifically as I haven't read it, but it could have a vampire as the main character, perhaps a young vampire trying to find its place in the world.
Obviously, Naruto would be one of the main characters. He's the central figure in the Naruto series, especially when it comes to his early days as a shinobi. His friends like Sasuke and Sakura would also likely be main characters as they were always by his side during his initial shinobi experiences.