Sasuke can also be a main character in Naruto Fire Temple fanfictions. His complex personality and his own journey of redemption or power - seeking can intersect with the events at the Fire Temple. Maybe he goes there to find a way to control his new - found powers or to seek answers about his clan's past that are somehow related to the temple.
Obviously, Naruto is the main character in most 'Naruto Ruler' fanfictions. But other characters like Sasuke also play important roles. Sasuke might be Naruto's advisor or a powerful ally in maintaining the rule. Sakura could be the head of the medical department, providing essential support to the village under Naruto's rule.
Often, Naruto himself can be a main character. He might be exploring the new power of dark fire, either trying to master it for the good of the village or facing the internal struggle of whether to use such a dangerous power. Sasuke could also be a main character. Given his own complex relationship with power and his past, he could be drawn to the allure of dark fire and how it could help him achieve his goals.
Blake Belladonna is another common main character. Her journey of self - discovery and her fight against the White Fang can be a major part of the fanfictions. Her 'shine' could be in her ability to find her true self and stand up for what she believes in, all while being a key member of Team RWBY.
I'm not entirely sure as it depends on the specific fanfiction. But it could be the main characters from the original work around which the fanfiction is based.
Obviously, Bella, Edward, and Jacob are likely to be main characters as they are central to the original Twilight story. Their relationships are so complex and full of drama that fanfiction writers often like to explore them further.
Daenerys Targaryen is often a main character. Since Dragonstone was an important place for the Targaryens, many fanfictions revolve around her connection to it. She might be exploring the secrets of the place or using it as a base for her conquests.
Often, Harry Potter himself can be a main character in these fanfictions. He might be the one to encounter the wraith and try to figure out its motives and how to deal with it, using his skills and knowledge of magic.
The clones are often main characters. They are the ones who execute Order 65, so fanfictions explore their motives and feelings. Some clones might be remorseful, while others are just following orders blindly.
Harry Potter himself is often a main character in these fanfictions. As he already has a natural inclination towards facing challenges and has a connection to powerful magic, it's easy to imagine him as a Dragonlord. He could use his newfound power to fight Voldemort in different and more powerful ways.
Sasuke can also be a main character in some fanfics. For example, there could be a story where Sasuke finally comes back to the village and Naruto takes him to Ichiraku to have some ramen as a way of welcoming him back. Kakashi might also make an appearance in such fanfics, as he is Naruto's teacher and might join them for a bowl of ramen.