Tobias Whale's henchmen can be considered underrated. They could be given more depth and backstories in fanfiction. For example, one of them might be having second thoughts about working for Tobias. Or there could be a character like Reverend Holt who could play a bigger role. He could be a moral compass not just for the community but also for Black Lightning in some difficult situations.
Some of the students at Garfield High School are underrated. They could be more involved in the metahuman drama. Maybe one of them discovers a new power and Black Lightning has to guide them. Or they could form a sort of support group for metahumans at the school, which could lead to all kinds of interesting storylines.
Lala is often an underrated character in Black Lightning fanfiction. He has a complex backstory as a gang member turned metahuman. There's a lot of potential to explore his redemption arc or his struggle between his old life and his new powers. Another could be Inspector Henderson. He's often in the background but could be developed more. He could have his own investigations that cross paths with Black Lightning in interesting ways.
One underrated character is Tyson. He has so much potential for a fanfiction focus. He's a Cyclops, which makes him different from the other demigods, and his loyalty to Percy is really heartwarming. A fanfiction could explore his backstory more, like his life before he met Percy at Camp Half - Blood. Another underrated character is Clarisse. She's often seen as just a bully, but there could be a lot more to her. A fanfiction could show her softer side and what made her the way she is, perhaps a story about her first quest and how it changed her.
Static Shock would be a great character to pair with Black Lightning. They both have electrical - based powers, and their combined abilities could create some really cool fight scenes. They could also learn from each other, like Black Lightning sharing his more experienced combat knowledge with Static Shock. Another good character would be Cyborg. Cyborg's technology - based powers and his connection to the Justice League could bring a different dynamic. He could help Black Lightning upgrade his equipment or provide intelligence on villains.
Sasuke is another popular choice. Given his thirst for power and his natural aptitude for lightning - based techniques, fanfiction writers often explore how he would obtain and master the Black Lightning. It could be a part of his journey to become even stronger and seek revenge against his enemies.
An underrated character is Cotton. His parrot is always a fun addition, and he could be the focus of a fanfiction. Maybe the story could be about how he lost his tongue and his journey before joining the crew. It would give a new perspective on the story.
Gauche Adlai is another underrated character. His Mirror Magic is really interesting. A fanfic could center around him and his relationship with his sister. Maybe he goes on a journey to find a way to completely bring his sister back to life, and in the process, he discovers new aspects of his magic that he didn't know before. He could also face some moral dilemmas about using his magic in extreme ways for his sister.
Naruto himself is likely to be one of the main characters. Since it's a Naruto fanfiction, he would probably play a central role. Maybe he'll be the one who discovers the power of Black Lightning and tries to incorporate it into his own fighting style. Another likely character could be Sasuke. He's always been Naruto's rival, and if Naruto starts using new powers, Sasuke would surely be interested in it too.
I don't know the specific main characters in this novel as I haven't read it.
In some fanfictions, it could be an enemy-turned - ally. This character, who originally fought against Naruto, realizes his strength and potential and decides to teach him black lightning as a way to make amends or to join forces with him for a greater cause.
Mezo Shoji is another one. His multiple - armed quirk could be used in so many creative ways in fanfiction, but he's not often the main character. There could be stories where he uses his arms not just for combat, but also for things like creating elaborate structures or helping in rescue operations in a unique way that other characters can't.
One underrated character is Yelena Belova. In fanfiction, more could be done to explore her relationship with Black Widow before and after they both left the Red Room. There could be stories about their training together, the competitions between them, and how they eventually reconciled. Another character is Madame B. Fanfic could dig deeper into her motives for running the Red Room so harshly and what led her to become such a cold - hearted figure.