Definitely the Grimm sisters themselves, Sabrina and Daphne. They are the main characters and their relationship and growth are central to the story. Another great character is Puck. His mischievous nature and his evolving relationship with the sisters can add a lot of fun and drama to a fanfiction. Mr. Canis is also interesting as he has a complex past and his loyalty to the sisters can be explored in depth.
The Grimm sisters are the obvious choice, but characters like Jack the Giant - Killer can be really fun to focus on. He has his own story and his bravado can be a great contrast to the more cautious approach of the Grimm sisters. Also, Granny Relda is an important character. Her wisdom and her role in raising the sisters can be explored in a fanfiction. And then there's Red Riding Hood, who has her own secrets and her connection to the fairy - tale world can add depth to a story.
In Sisters Grimm fanfiction, focusing on the Big Bad Wolf (Mr. Canis in his human form) can be really cool. His internal struggle between his wolfish instincts and his human side can create a lot of tension. Also, the Fairy Godmother is an interesting character. She has a lot of power and her motives are sometimes a bit mysterious. And don't forget about the Evil Queen. She has a rich backstory and her interactions with the Grimm sisters can be full of intrigue.
Sabrina and Daphne are really popular. Sabrina with her more headstrong and cynical nature often makes for great conflict and growth in stories. Daphne, being the more optimistic and naive one, can also drive interesting plots. Puck is another fan favorite. His mischievous nature and powerful fairy abilities can add a lot of fun and chaos to a fanfiction.
When reading The Sisters Grimm fanfiction, try to engage with the community. Leave comments on the stories you like, or join forums where fans discuss their favorite fanfictions. This can enhance your overall experience as you get to share your thoughts and hear others' perspectives. You might also discover new fanfictions through these interactions.
The main family members can be great to focus on. Their relationships, power struggles, and dreams offer a lot of material. For example, the patriarch of the family who has to make tough decisions to keep the ranch going. Another good character could be the strong - willed matriarch who holds the family together. Also, the young and rebellious heir who wants to do things his own way.
Fox Alistair is an underrated character that would be interesting in RWBY Grimm Verse fanfiction. He's blind but has amazing combat skills. A story could be about him using his other senses to detect and fight Grimm in a way that others can't. Also, there's Coco. She has a very distinct style and her weapon is really cool. A fanfiction could explore how she uses her fashion sense and her weapon to take on different types of Grimm in a more creative way than we've seen before.
Sersi is a great character to focus on. She has a strong connection to humanity and her powers are quite interesting. You could explore her relationships with humans in more detail. Another good one is Ikaris. His loyalty and the internal conflict he might face are good material for a fanfiction. Then there's Kingo, with his love for movies and his unique charm among the Eternals.
All of the members of 4 town are great to focus on in different ways. Tae Young, for example, might be the subject of a fanfiction where his amazing dancing skills are the center of the story. Maybe he gets an offer to be in a big dance competition outside of the band, and he has to decide whether to take it or stay loyal to 4 town. Each member brings their own unique traits that can be explored in fanfiction.
The friends of the main couple can also be great to focus on. They can add humor, support, or even create some conflict. For example, a friend who is always teasing the couple about their relationship can be a fun addition to the fanfiction.
Sebastian is a fun character to focus on. You can write about his loyalty to Ariel and how he tries to keep her out of trouble. He could have his own mini - adventures in a fanfiction, like getting lost in the human world while trying to find Ariel. Flounder is another good one. You could show his growth from a timid fish to a more brave friend of Ariel's. Also, Triton, Ariel's father, can be a central character. You can explore his relationship with Ariel in more detail, like his struggle to let her go.
In my opinion, Magnus Bane could be a great character to focus on in Clockwork Angel fanfiction. He has such a flamboyant personality and his magic abilities are quite interesting. He could interact with the main characters in ways that haven't been explored in the original story. Another good character would be Charlotte. As the head of the Institute, she has a lot of responsibilities and secrets that could be delved into. And of course, Tessa. She is the center of the story in many ways, and her character development is something that can be further explored in fanfiction.
Obviously, Bella herself is a great character to focus on. She's the main character and has so much potential for different storylines. You could explore her growth as a football player and as a person.