The main characters could include the leaders of the Freys. They would be the ones making the decisions on how to deal with the dragon attacks. And the dragon itself, which might have unique characteristics or abilities that make it a formidable foe. Additionally, there could be a wizard or sorcerer who either tries to control the dragon or help the Freys defend against it. They would play important roles in the story as they bring different elements of power and knowledge to the situation.
The plot might involve the dragon seeking revenge on the Freys for some past wrong. Maybe the Freys had wronged someone the dragon was attached to, so it attacks their strongholds, burns their lands, and causes chaos among them.
There could also be other supporting characters. For instance, Naruto might make an appearance. Since he's Sakura's friend and also has a connection to Itachi through Sasuke. Naruto could come in to try and stop Itachi from attacking Sakura, adding another layer of conflict and drama to the story. Or Kakashi could be there. He's their teacher and has a good understanding of both Itachi and Sakura's capabilities, so his presence could change the course of the story as well.
A young girl who has always been fascinated by dragons could be a main character. She might be an outcast in school until she discovers her ability to communicate with dragons.
Well, for a Dragon Ball harem fanfiction, Goku is a top candidate for the main character. He's the hero of the series, and his naivete about relationships combined with his strength would be really interesting in a harem setting. Bulma could also be a main character in a different way. She's smart and sassy, and if the fanfiction focuses on a female - centered harem, she could have a group of male Dragon Ball characters attracted to her. Additionally, Goten could be a main character. He's young and has a lot of potential for growth in a story where he has a harem of his own, with female characters seeing his potential as a future powerful Saiyan.
A group of fairy siblings. They are very mischievous but also very kind - hearted. They can offer their unique fairy magic to assist Jane and the dragon. For example, they can create illusions to deceive their enemies or use their small size to get into places that are otherwise inaccessible.
Trunks could also be a main character. He's from the future and has a cool attitude. In the fanfiction, he could be the new kid at school, trying to fit in while also having to deal with threats from his own time that somehow follow him to the school.
Another possible main character could be an old wise man who has known about the noodle dragons for a long time. He could guide Genji in his interactions with the noodle dragon, providing historical and cultural context. And of course, the noodle dragon itself could be a main character with its own personality and motives.
An alchemist who is trying to study and harness the power of the dragon's fire could be a main character. They might be on a quest to find a way to use the fire for good, like curing diseases or creating powerful magic items.
A dragon tamer could be the main character. They have a special bond with the dragon and use the dragon's roar to their advantage in battles or to solve problems.
An old and experienced dragon slayer who has seen many battles and has a lot of wisdom to pass on. He could be a mentor figure to the younger slayers, but also has his own secrets and past traumas related to the dragons that could be explored.