There's the lone survivor who is often the main focus. This character has to use their wits to stay alive in the unforgiving environment.
Since we don't have much information about 'the long dark story', it's hard to say for sure. However, it might have a protagonist who is a strong - willed individual, like a hunter or an explorer. There could also be supporting characters such as a wise old man who gives advice, or a young sidekick who is learning the ropes of survival in this long dark situation.
I'm not familiar with this specific story, but typically in a story about a long, dark situation like this, there might be a protagonist who is the central figure going through the challenges. There could also be an antagonist, perhaps in the form of the harsh environment or other people who are causing trouble for the main character. And there may be some side characters like a friend or a mentor who offer support or guidance at certain points.
Since I don't have much information about this story, I can't say for sure who the main characters are.
Since I haven't read the 'long dark water story', I can only guess. There could be a protagonist who is on a quest related to the long dark water. It might also have a wise old character who imparts knowledge about the water's secrets. There could be a sidekick character as well to accompany the main character on their journey.
An adventurer might be a main character. They are used to facing challenges and the dark room is just another mystery for them to solve. They might bring their tools and knowledge to deal with whatever is in the room.
Obviously, the Dark Magician is one of the main characters. It's the central figure in these duel stories.
Maybe there are some characters who are known for their unique duel styles in 'Dark Duel Stories'. For example, one character might be really good at using speed - based strategies during duels. And there could be an antagonist as well, who constantly tries to disrupt the dueling order or defeat the main character.
There could also be villains as main characters in 'dark pokemon stories'. These could be people who want to use pokemon for evil purposes, like a team that wants to control the world by using powerful and dangerous pokemon. They create a lot of conflict and are the source of the 'dark' elements in the story.
I'm not sure specifically as I haven't read the 'the dark stone stories' in detail. But there could be a brave hero who is on a mission related to the dark stone.
Often, the main character is the dark angel itself. It can be a solitary figure with a complex personality.