Without more knowledge of the 'black demon story', it's a bit of a guess. It could be that there is a family that is being terrorized by the black demon. The parents trying to protect their children, and among the children, there might be one who has a special connection or ability that could potentially be used to fight the black demon. Or perhaps there is a solitary hunter - type character who has made it his mission to track down and destroy the black demon.
Since we don't have details about the 'black demon story', the main characters could include the black demon itself. There might also be a victim or a group of victims that the demon preys on. And perhaps there is a wise old character, like a wizard or a priest, who has knowledge about the demon and tries to stop it.
I'm not sure specifically as I haven't read the exact 'Black Heart Demon' Wattpad story, but usually there would be the protagonist who might be a hero or a regular person caught up in the events related to the Black Heart Demon. There could also be a mentor - like figure who helps the protagonist face the demon.
The main characters in the 'demon days story' could be diverse. There could be a group of survivors who have banded together during the demon days. Among them, there might be a brave warrior who is skilled in combat and not afraid to face the demons head - on. There could also be a mysterious seer who can foresee some of the events related to the demons and helps the group make decisions. And then there are the demons themselves, which might have different personalities and motives. Some demons could be more bloodthirsty, while others might be more calculating and have their own long - term plans for the demon days.
Typically, there is the human who becomes involved with the demon lover, and of course, the demon lover itself.
In the 'demon lover story', the main characters usually consist of the demon lover, which could be a male or female demon with different abilities and motives. The other main character is the human who becomes entangled in the demon's world. This human might be an ordinary person living an ordinary life until the demon enters their life, bringing chaos, love, or a mix of both. There could also be other secondary characters like friends or family of the human who react to the situation in different ways, either trying to protect the human or being afraid of the demon.
Since I don't know the exact 'demon in the dark story', it's hard to say. But it could be a brave hero who tries to fight the demon.
There's David Mason too. He's involved in many of the key events in the main story, especially those related to the future part of the plot.
Not having read 'the black farm story', it's hard to determine the main characters. However, they could potentially include a strong - willed black female farmer who is breaking gender and racial barriers in the farming world. Her children might also be main characters as they grow up on the farm and face different challenges. Additionally, there could be a local advocate who fights for the rights and success of the black farm in the face of external pressures like big corporations trying to buy the land.
I don't know for sure, but if it's about black eagles in nature, the main characters could be the eagles themselves. Maybe a male and a female eagle that are building a nest and raising their young.
Since I don't know the specific 'the black coffin story', it's hard to say. It could be the person in the coffin, or the people who discover the coffin.