Obviously, Catra and Adora are the central characters. Their relationship forms the basis of the family in the fanfic. And likely their children, if they have any in the story, would also be important characters.
One popular theme is the family's adventures together. They might go on quests or explore new lands. Another theme could be how they handle challenges as a family, like dealing with outside threats or internal conflicts within the family unit.
I'm not sure exactly who the main characters are without reading it, but it's likely the family members themselves, like the parents, kids, and maybe grandparents if it's a multi - generational family.
One common theme is the symbolism of the jackets. They often represent the connection between Catra and Adora, like a physical manifestation of their bond. For example, in many fanfics, when one gives the jacket to the other, it's a sign of trust or a new level of closeness.
In a 'family ties rwby fanfic', characters like Qrow could also play a major role as he is Ruby's uncle. His relationship with Ruby and his influence on her growth as a huntress can be a significant part of the story. Also, if the fanfic explores Blake's family, her parents or any other relatives in the Menagerie could be main characters as they are related to her family ties.
Akashi Seijuro is often one of the main characters. His strong personality, leadership skills, and complex family background make him a central figure. His father is also usually an important character as he represents the head of the Akashi family and often has a big influence on family decisions.
Catwoman might also be a main character. Even though she has her own motives, in this fanfic she could be involved with the bat family in some way, either as an ally or a more complex relationship. Her skills in thievery and acrobatics would add an interesting dynamic to the story.
Obviously, the Warner siblings - Yakko, Wakko, and Dot - should be the main focus. Their unique personalities and the way they interact with each other can create a lot of interesting storylines. Pinky and the Brain could also be important, especially if you want to include their mad - scientist - like experiments in the family - centric story.
The main characters would likely be the RWBY team members - Ruby, Weiss, Blake, and Yang. Since it's about meeting the family, their families would also be important characters in the fanfic.
Typically, the members of the Wyatt family would be the main characters. They would be the ones whose actions drive the story forward in the Naruto - themed setting. But Naruto and his closest friends might also be important characters as they interact with the Wyatt family.
There might also be other extended family members or friends who play significant roles. For example, an old wizard friend of Albus who has known the family for a long time and often comes to visit and offer advice during difficult times.