Definitely the two main characters. The young boy, Takao, is interesting because of his dreams and his growing maturity. Writers can explore his thoughts and feelings as he transitions from a boy to a young man. Yukari, the woman, is also a great character to write about. Her mysteriousness and the reasons behind her actions can be delved into in fanfiction.
Fine is also a popular choice. Her position as a vampire yet having some sympathy towards humans offers a lot of room for exploration. Fanfiction can delve into her internal conflicts, such as her loyalty to her vampire kind and her growing connection with humans.
For me, Sol Star is an interesting character to write about in deadwood fanfiction. He's often in the background but has his own dreams and desires that can be further developed. Then there's E.B. Farnum. His conniving and somewhat pathetic nature can be a source of great comedic or tragic stories. And of course, Wild Bill Hickok. His legend and his short time in Deadwood provide a lot of inspiration for different storylines.
Link is a very interesting character. His complex backstory with the Triforce and his many adventures in Hyrule give a lot of material for fanfiction. You can write about his internal struggles, like when he has to make tough decisions to save his kingdom. Another interesting one is Kirby. His cute appearance but powerful abilities create a contrast. You can write about Kirby exploring new planets and befriending other SSB characters.
In my opinion, the Death Knight can be a very interesting character for quake fanfiction. It has this dark and menacing presence. You could write about its past, like how it became this powerful and feared entity. Another interesting character is the Fiend. You can explore its relationship with other creatures in the Quake world, or how it hunts its prey. And the Vore is also an interesting one. It has this unique and grotesque appearance, and you could write about how it came to be in the Quake universe.
Yato is definitely one of the most interesting. His complex personality, with his past as a war god and his current quest for recognition, gives a lot of material for fanfiction. Hiyori is also great. Her ability to cross between the worlds and her kind - hearted nature make her a fascinating character to explore in different scenarios. And Yukine, with his growth as a shinki and his relationship with Yato, offers a lot of potential for interesting stories.
Elise is a really interesting character to write about. Her grace and skill on the slopes make for great descriptions. Mac is also cool. His laid - back attitude combined with his amazing stunts gives a lot of material for fanfiction. And then there's Zoe. Her bubbly personality and determination can add a lot of charm to a story.
Max Sterling is an interesting character for robotech fanfiction. He's an ace pilot with a cool - headed nature. His relationship with Miriya, a Zentraedi who becomes his wife, is full of potential for stories. Lisa Hayes is also great. Her strong leadership and her evolving feelings for Rick Hunter can be the focus of many interesting plots. Then there's Khyron, the unpredictable Zentraedi who always brings chaos and danger.
For me, Jasper is really interesting in Twilight fanfiction. His past as a Confederate soldier and his struggle with his bloodlust are great elements to explore. Victoria is also a character that offers a lot. Her thirst for revenge against the Cullens can be the basis for some really intense and action - packed fanfiction. And Emmett, with his big and boisterous personality, can be used to add some humor and light - heartedness to the often - dramatic Twilight fanfic world.
The fox spirit characters are often very interesting to write about. Their mischievous nature and their unique abilities make for great storytelling. For example, their ability to transform gives writers a lot of creative freedom. They can be written as cunning yet loveable characters, always getting into and out of tricky situations. Another interesting character is the human male lead. His reactions to the supernatural world around him can be explored in many ways. How he copes with the attention of the fox spirits and other supernatural beings can create engaging storylines.
The Flash is an exciting character to write about in Wonder Fanfiction. His super - speed can lead to all kinds of creative scenarios. He could be racing to save the day in a situation involving Wonder Woman and other heroes. Aquaman is also interesting. His connection to the ocean and his role as a king can create unique storylines. Maybe he's negotiating with Wonder Woman about some underwater - related issue, or they're teaming up to face a common threat from the deep sea.