Often, there are young protagonists. Since the concept of innocence is closely related to youth, these young characters are at the center. They could be teenagers in a dystopian world who start off with an innocent view of how things should be but are quickly faced with the dark underbelly of their society.
There might also be mentor - like characters who have already lost their innocence and serve as a contrast to the more innocent ones. For example, an old wizard who has seen the dark side of magic for years and now guides a young, innocent apprentice who is about to discover that same darkness. These mentor characters can help highlight the transformation of the innocent characters.
Often, there is a brooding, mysterious character. This type of character may have a troubled past that colors their view of love, leading them to exhibit the darker aspects of love such as being overly controlling.
One common theme could be the loss of naivete. In this type of fanfiction, characters might start out innocent but then face situations that shatter that innocence, like being exposed to the harsh realities of a fictional world, such as betrayal within a magical community they once thought was harmonious.
There's often the 'dark ash' character who is at the center of the betrayal. There could also be a friend or ally who turns out to be the betrayer. Another typical character might be someone who stands by the 'dark ash' after the betrayal, perhaps a true friend or a love interest.
I'm not sure specifically, but it could be a group of scientists. They would be the ones with the knowledge and curiosity to venture towards the sun's dark side.
Well, of course, the dark mother herself is a central character. She is likely to be a complex figure, with both positive and negative traits. There might also be a child or children of the dark mother. These characters could be in a struggle to understand their mother's love, which may not be expressed in a typical way.
Obviously, Jessica is a main character since she's in the title. There might also be characters who oppose her rule in the dark side. Maybe there are some sidekicks or allies that help her maintain her power.
Sasuke is often a popular character in Naruto dark side fanfiction. His natural brooding nature and his own internal struggle with power and revenge can be easily explored in a darker context. Another one is Itachi. His complex backstory and the secrets he held can be further delved into in a darker version of the Naruto world.
Darth Vader is often a very popular character. His iconic status in the Star Wars universe makes him a natural fit for fanfiction about the dark side of the Force. Another popular one is Darth Maul, with his menacing appearance and unique fighting style. Kylo Ren is also quite popular as he represents a more conflicted character who is drawn to the dark side.
There are often innocent victims. These are ordinary people who just happen to be in the wrong place at the wrong time. Then there are the villains. They could be supernatural beings like vampires or werewolves, or just really evil humans. And sometimes there are the wise old characters, like an old hermit who might know something about the dark secrets but is often reluctant to get involved.
Children are very typical characters. They often have a natural fear of the dark, and in these stories, they might be the ones cowering under the covers or trying to brave their way through a dark room. Another common character is the lone traveler. They find themselves in a dark and spooky place, like an old inn or a desolate road at night. And there are also the old wise characters, like an old hermit who might know the secrets of the dark and either help or hinder the main character.