I don't have enough information to say who the main characters are as I don't know the particular 'a light in the darkness story'.
In some 'a light in the darkness' stories, the main characters could be a group of people. For instance, a group of oppressed workers. One of them might emerge as a leader, with some special qualities or ideas, and this person could be like the 'light' that guides the rest of the group towards a better future, fighting against the unjust system they are in. They all play important roles in the story as they interact with each other and the situation around them.
I'm not sure specifically as we don't have more details about the story. But it could be an ordinary person who becomes a hero, like a young girl who finds a cure for a deadly disease in a world full of suffering. She would be one of the main characters.
There's no way to accurately name the main characters without having read the 'In Darkness 2018 Story'. However, in a story about 'darkness', it's common to have a central figure who is in the middle of the turmoil. This character could be an everyman type, someone who the readers can easily relate to. There might also be antagonists, perhaps people or forces that are causing or contributing to the 'darkness' the protagonist is facing.
I'm not sure who the main characters are without more information. It could be a group of brave explorers or just one person on a solo journey into the darkness.
Maybe there is a protagonist who has some special ability to combat the darkness, and there could also be some side characters who either help or hinder the protagonist's journey in the 'the darkness 1 story'. Without more context, it's difficult to be more precise.
Since I don't know the details of the 'darkness 2 story', I can't say who the main characters are.
Since I don't know the exact 'the darkness story', it's hard to say. But it could be a lone hero who has to face the terrors of the darkness. Maybe it's a young child who is the only one seeing the strange happenings in the dark.
Kazuma is one of the main characters related to Darkness. Their relationship is full of comical exchanges. Also, Aqua and Megumin are important characters in relation to Darkness. They are all part of the same party in the story.
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.
I'm not sure as it depends on the specific fanfiction. It could be an original character created by the author who is trying to find their way out of a dark situation.
In Brynhildr in the Darkness light novel, Ryota Murakami is a key character. He is a normal boy at first but then becomes crucial in the story of the Brynhildr girls. There's Brynhildr, who has special abilities and a complex personality. Other important characters are the other Brynhildr girls, each with their own powers and stories, and they all play important roles in the overall plot.