It could still be Harry Potter himself. He has a history of facing dangerous creatures and dark magic, so it would be natural for him to take on the challenge of the deadly snake.
Another possibility is that a new character is introduced as the main character. This character could be a transfer student from a far - off magical school who has some special knowledge or ability related to snakes. They come to Hogwarts just as the deadly snake situation unfolds and end up being the key to solving the problem.
One possible plotline could be the discovery of a new type of deadly snake in the Forbidden Forest that has some mysterious connection to dark magic. Maybe the snake is guarding a long - lost artifact.
Ron could also be the main character. He has his own courage and loyalty. He could be the one who has an unexpected connection with the poisonous snake, like being able to communicate with it in a special way that no one else can.
Another option could be a new character. A transfer student, perhaps, who is really a Slytherin at heart but is placed in Gryffindor by mistake. This character then has to keep up the pretense of being a Gryffindor while dealing with their true Slytherin nature.
Obviously, Harry Potter is one of the main characters. And the snake, which could be a unique creation within the fanfiction, is also a main character. It might have its own personality and abilities that are different from normal snakes in the Harry Potter universe.
Another example could be a fan - made deadly curse. Some fanfictions create their own curses that are just as deadly as the ones in the original series. These new curses can have unique effects and ways of being cast. For example, a curse that slowly drains a person's life force instead of killing them instantly like Avada Kedavra.
In Harry Potter fanfiction, deadly curses often add a darker and more dangerous element. For example, the Unforgivable Curses like the Killing Curse. Fanfic authors might explore how characters are affected by these curses in different scenarios. They could show a character narrowly escaping a deadly curse, which heightens the tension and drama in the story.
In some fanfictions, Voldemort could also be a key character in relation to the snake king. Since Voldemort had a connection with snakes, he might either be in conflict with the snake king for power or try to control it. Additionally, there could be original characters created for the fanfiction. For example, a young wizard who has a special gift for understanding snakes and becomes the mediator between the snake king and the human wizards. This character could bring a fresh perspective to the story and help in building a relationship between the two very different worlds of humans and the snake king.
Obviously, Harry Potter would be one of the main characters. And the snake, which plays a crucial role as per the title. There might also be other characters from the original series like Hermione and Ron, who could interact with Harry in the context of his new relationship with the snake.
It could be Nagini. Even though in the original series she was more of a servant to Voldemort, in the fanfiction, she could have a different personality and form a bond with Harry.
It could also be a snake from the Forbidden Forest. There are many unknown and mysterious creatures in there. A snake from that forest might be more in tune with the natural magic of Hogwarts. Harry, being the curious and kind - hearted person he is, might come across it during one of his adventures in the forest and start a friendship with it.