I'm not sure specifically without more details about this 'Black Widows Series Story'. But generally, there would likely be at least one character named Black Widow who is strong, smart, and skilled in combat and espionage.
Typically, the black widow characters themselves are the main characters. They are often complex women with their own backstories and motives.
The Black Widows Series Story could be about a group of female characters often associated with the name 'Black Widow'. It might involve their adventures, their skills, and the challenges they face. Maybe it's about their origin stories, how they became the strong and mysterious figures they are, and the relationships they have with other characters in their fictional world.
The main theme could be revenge. In many 'black widows' stories, the female characters often seek revenge for the wrongs done to them.
One of the main characters is Alex Mason. He is a key figure in many of the operations. Another important character is Frank Woods. These two are often at the center of the intense action and dangerous missions in the story.
The main character in the Black Widow web series story is Natasha Romanoff, of course. She is the Black Widow. Yelena Belova is another significant character. She and Natasha have a complex relationship, perhaps as sisters in the context of the Red Room. There might also be characters from Natasha's past in the Red Room, like her trainers or other Black Widows, who could play important roles in the story.
I'm not sure as I haven't read it, but it could be the black fox character if there is one. Maybe some original characters created by the fanfic writer who interact with the MHA canon characters.
Since I don't know the exact 'Black Bird Series Story', it could be that the main character is the black bird itself. It might be a solitary bird with a unique personality.
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.