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.
Steve Randle is often overlooked. He could be explored more in fanfiction. He's a loyal friend to Sodapop and has his own dreams and fears. Fanfiction could show his life outside of just being a greaser, like his relationship with his family or his plans for the future.
Ser Harwin Strong is quite an underrated character. In fanfiction, you could explore his relationship with Rhaenyra more deeply. What were his true feelings? Another one is Mysaria. She has a lot of potential for exploration. Her role as a spy and her connection to Daemon could be delved into further. And there's also Laenor Velaryon. His story as a gay man in a society that may not fully accept him could be expanded in fanfiction.
In crestfallen Harry Potter fanfiction, some underrated characters that could be explored are Hannah Abbott. She has a connection to Hufflepuff house, and in a situation where things go wrong in the wizarding world, her loyalty and determination could be put to the test. Also, Blaise Zabini. He has an air of mystery around him, and in a crestfallen scenario, his family secrets could come to the surface and cause him distress. And then there's Parvati Patil. She has been more of a side character, but in this type of fanfiction, her experiences with magic and her relationships could be explored more deeply, especially if she is facing a situation that makes her feel crestfallen, like a rift in her friendship with Lavender or a setback in her magical studies.
Murtogg is another character that could be explored more. He seems to be a bit of a follower, but there could be a story where he has to take charge. Maybe in a situation where the cursed crew is in a new kind of danger and he has to make decisions that go against his usual timid nature. This could show a different side of him and make for an interesting fanfiction.
A great plot could be a what - if scenario. For example, what if Black Widow had managed to expose the Red Room much earlier? This could involve her teaming up with an unexpected ally, perhaps a S.H.I.E.L.D. agent who stumbles upon her mission. They would then have to work together to take down the Red Room from the inside out, facing all the dangerous obstacles and mind - games the Red Room is known for.
Agent Madani is also somewhat underrated. Fanfiction could show more of her backstory and how she really feels about working in a world full of crime and violence. She could be given more complex relationships with other characters, not just Frank. For example, her interactions with other law enforcement agents or even some of the criminals she has to deal with.
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.
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.
Molly is often overlooked but has great potential. In fanfiction, we could explore more of her relationship with her father and how that affects her role as a Starcatcher. We could also see her develop her own unique magical abilities beyond what's shown in the original story.
Huntress could be a great choice. She has her own sense of justice and skills that could add an interesting dynamic to the Knightfall story. Another one is Azrael. He has a complex backstory and his presence during Knightfall could be explored more deeply.