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.
Perhaps there are two main characters. One could be a lost traveler in a desolate land, and the other could be a wise old hermit who shows the traveler the way out, both of them playing crucial roles in the 'light in the darkness' narrative.
There might be a group of main characters. For example, in a story about a city facing a mysterious darkness that is making people ill. A doctor, a scientist, and a brave journalist could be the main characters. The doctor tries to find a medical solution, the scientist investigates the cause, and the journalist spreads awareness. Together, they are the lights in the city's darkness.
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'.
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.
Since it's a Twilight fanfiction, it might focus on the Cullens as the main characters. One of them could be the one to bring the 'light in the darkness'. For instance, Carlisle with his moral compass and leadership could be the central figure in a story about guiding the family through a difficult time in the Twilight - like world. Or perhaps it could be a new Cullen - like vampire introduced in the fanfiction who plays this role.
It's hard to say exactly who the main characters are without reading the fanfiction. But if we consider the themes of 'darkness in the light', it could be characters who are on the verge of losing their way in the light - filled Yu - Gi - Oh world. It might be some of the minor characters from the original series who are given more depth in this fanfiction. For example, a character who was always in the background but now is in the center of a story arc dealing with the discovery of a dark power within a seemingly innocent card. Or it could be an entirely new character created by the fanfiction author who has a unique connection to both the light and the darkness in the Yu - Gi - Oh universe, and through their journey, we explore the concept of 'darkness in the light' more deeply.
It's hard to say without reading it. But it could be the usual Twilight characters like Bella, Edward, and Jacob. Maybe it also features some minor characters from the original series in more prominent roles.
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.
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.