Frodo Baggins from 'The Lord of the Rings' is a badass in his own way. He undertakes a seemingly impossible task of destroying the One Ring, facing countless perils along the way. He has a quiet strength and an unwavering resolve. Rand al'Thor from 'The Wheel of Time' is another. He has the power to channel the One Power and is fated to either save or destroy the world. His journey is filled with battles, both internal and external, which he bravely faces.
In 'A Song of Ice and Fire', Arya Stark is extremely memorable. She's a young girl who becomes a badass assassin. Her journey from a naive child to a skilled killer, learning the ways of the Faceless Men, is amazing. Another is Geralt from 'The Witcher' series. He's a monster hunter with his own code of ethics, and his battles against all kinds of terrifying creatures are badass. And in 'The Name of the Wind', Kvothe is unforgettable. His intelligence, his skills in magic and music, and his ability to get into and out of trouble are what make him such a great and badass character.
Obviously, Bella is one of the main characters as it's named after her. There might also be other characters like her friends who support her in her badass adventures, or her enemies who she has to face off against. It could also include love interests, depending on the nature of the story.
Issei is the central figure in 'badass issei fanfic'. But there are other characters too. For example, the villains he faces. They are designed to test his new - found badass skills. And then there are his comrades from his group who interact with him in different ways, depending on how his badass personality affects the group dynamics.
Obviously, Bella is one of the main characters since it's about her being a badass. There might also be other characters from the original story she is from, like Edward or Jacob, who could be involved in the new storylines around badass Bella.
One of the badass fictional characters is Wolverine from X-Men. He's tough, has amazing healing powers, and never backs down from a fight.
Well, Akko is obviously the main character in 'badass Akko fanfic'. But often, her friends like Lotte and Sucy also play important roles. They might support Akko in her badass adventures, or sometimes they even get into trouble that Akko has to bail them out of.
Obviously, Naruto is the main character. He's the one who is going to transform into this badass figure. Sasuke might also play an important role. He could be Naruto's rival - turned - ally or vice versa. Their relationship always adds depth to the story.
Obviously, Ash is one of the main characters. He's the one who experiences the betrayal and then transforms into a badass.
Another possibility is that there are characters from different timelines or dimensions because of the reincarnation concept. For example, he might meet versions of himself from other lives, or people who were important in his past existences. These characters would add more depth and complexity to the story, as Harry has to navigate his relationships with them while also dealing with his present - day situation in the wizarding world.
Well, it could be characters like Draco Malfoy. In the original series, he had his moments of growth and in fanfics, he might be one of the main Slytherins to defend Hogwarts. Maybe he finally realizes the importance of the school and his own values change. He could be joined by other Slytherins who were perhaps overlooked in the official story but show their true courage in the fanfic.