In most 'badass issei fanfic', Issei is front and center. He's the one with all the cool new abilities and the tough - as - nails attitude. Alongside him, you might find characters like Kiba who could be his ally in battles against powerful enemies. And of course, the antagonists that are there to oppose Issei's badass rise to power.
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.
One popular 'badass issei fanfic' is 'Rising Dragon of DxD'. It shows Issei in a more powerful and assertive role. Another one could be 'Issei's Ascent' which really focuses on his growth into a badass character.
In many of these fanfics, the tinker taylor is of course a main character. They are often portrayed as highly skilled individuals, maybe with a bit of a rough exterior but a heart of gold. Sometimes, there's also a sidekick character, like a young apprentice who learns from the badass tinker taylor.
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.
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.
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.
Batman himself is obviously one of the most popular characters. He is the central figure and the source of the 'badass' factor in the fanfic. The Joker is also very popular as he provides a great contrast to Batman with his chaos and madness. Harley Quinn is often included as well, with her complex relationship with the Joker and her own brand of insanity. Another popular character is Robin, who represents the sidekick and the future of Batman's legacy.
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.
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.