It's really hard to tell without reading it. However, in fanfiction, it's common for the main characters to be borrowed from the original work it's based on. So perhaps it features the main hero or anti - hero from the source material who is now being explored in a more in - depth, darker context.
Since I haven't read it, I can't say for sure. But it could be the protagonist who has this 'dark heart' that the title refers to.
The main character is Marlow. He is the narrator of the story and his journey into the Congo forms the core of the novel. Kurtz is another important character. He is a man who has become a sort of demi - god in the Congo, representing the extreme of what European influence can become in the African context.
The main character is Marlow. He's the one who embarks on the journey into the Congo. His perspective shapes the whole story. Kurtz is the most talked - about character. He's a man who has lost his way in the jungle, succumbing to the power and madness there. There are also the unnamed European managers and clerks. They are part of the machinery of imperialism, and their actions and attitudes help to show the nature of the colonial enterprise in the Congo.
I don't know for sure as I haven't read it. But it could be a protagonist who is struggling with some sort of inner turmoil or external conflict, and then there might be a secondary character who acts as the 'light'. For example, it could be a young wizard as the main character who is constantly battling his own dark magic tendencies, and then a wise old mentor could be the 'light' character.
Marlow is the central figure in Heart of Darkness. He's a seaman who is sent to the Congo to retrieve Kurtz. Kurtz, on the other hand, is this mysterious and somewhat infamous figure. He has created his own little 'empire' in the jungle and has lost his moral compass. There are also some other minor characters like the Manager, who is in charge of the trading post in the Congo, and the natives, who are often the victims of the colonizers' actions.
I'm not sure specifically as it could vary greatly. Fanfiction often takes existing concepts and twists them. It might be about exploring the dark aspects of a character's psyche or a dark event within a particular fictional universe.
Marlow is a very important character. He is the narrator of most of the story and his journey into the heart of Africa forms the core of the narrative. Kurtz is also crucial. He is a man who has gone deep into the Congo and has been corrupted by the power and the environment there. The Manager is another important character. He is in charge at the Company's station in the Congo and is often in conflict with Marlow and represents the more bureaucratic and self - interested side of the European presence in Africa.
The most important character is Marlow. He's the one who undertakes the journey up the Congo River and has all the encounters that form the basis of the story. Kurtz is another significant character. He has a sort of magnetic pull on Marlow and represents the extreme of what can happen to a man in that environment. Additionally, the Manager of the trading post is an important character as he is part of the power structure in the Congo and his actions and motives contribute to the overall atmosphere of the story.
I don't know the main characters in this story as I haven't read it.
Often, there is a central character who is on the path of mastering their heart. This could be a young adult who is dealing with complex emotions.
I'm not sure specifically as it depends on the fanfiction itself. But it could be an original character created by the author who has a special ability to perceive the darkness. Maybe it's a hero - type figure who is determined to fight against whatever the darkness represents.