There could be the last royal vampire themselves, of course. Then perhaps a loyal servant or advisor who has been with the vampire's family for generations. A hunter who initially wants to kill the vampire but then realizes they may be the key to something bigger is also a great character.
A witch could be an interesting character. They might be in a love - hate relationship with the last royal vampire. Maybe they once had a deal with the vampire's ancestors and now they are forced to help or hinder the current vampire depending on how the story unfolds. Another character could be a young vampire who looks up to the last royal vampire as a symbol of hope and wants to follow in their footsteps.
One idea could be exploring the origin of the last royal vampire's powers. Maybe there's a long - forgotten spell or a unique bloodline trait that gives them special abilities. Another could be a love story between the vampire and a human who is immune to their charm, which creates a lot of interesting conflicts.
Well, obviously Celestia herself is the central character. Then there could be a shy and gentle maid who has been secretly in love with Celestia for a long time. There might also be a bold and adventurous knight who defies the traditional gender roles of the kingdom and is attracted to Celestia in a yuri way.
A time - traveling rogue could be a great main character. He's not really on either side of the war but is just trying to survive and make a profit in the chaos. Maybe he stumbles upon a powerful time - based weapon and has to decide what to do with it.
A young vampire who is new to the vampire queen's court. This vampire is naive and still learning about the ways of the vampire world. He could provide a different perspective and also be a source of trouble as he makes mistakes and the vampire queen has to deal with the consequences.
Well, of course, there's the little vampire himself. He could have a best friend who is a human, a brave kid who is not afraid of the vampire's nature. There might also be an old vampire mentor who teaches the little one about vampire traditions and how to control his thirst.
It might also be possible for new characters to be the main characters in this fanfiction. For example, a young ninja who discovers a Keyblade and has to learn how to use it while also dealing with the politics and power struggles in the Naruto universe. They could be from a minor clan but rise to prominence through their Keyblade skills.
There could also be a mysterious outsider from another land. They've heard about the power of the Naruto world's bloodlines and come to steal them. This outsider might have their own motives, like using the bloodlines to strengthen their own people back in their homeland. They would be a completely new and unpredictable element in the Naruto universe, making for an interesting story as the characters try to figure out who this unknown thief is and where they come from.
Well, obviously Aquaman himself would be a key character. He could be a mentor to his daughter, guiding her in the use of her powers and in understanding her responsibilities. Mera, Aquaman's wife, could also be an important figure, perhaps teaching the daughter some of the more feminine aspects of Atlantean culture or how to control her water - based powers in a different way. Then there could be the daughter's friends, like other young Atlanteans who she goes on adventures with. They might have different powers or skills that complement hers.
There could be a wise old wizard who lives in a tower in Arcadia Castle. He has vast knowledge of magic and often gives advice to those in need. Another character could be a young and curious maid who always seems to stumble upon the castle's secrets while going about her daily chores.
You could include a wise old mentor figure, like an old gardener who gives Cinderfella advice. A friendly mouse that helps Cinderfella around the house. And of course, the beautiful princess who Cinderfella falls in love with at the ball.