In Only Murders in the Building fan fiction, we could introduce a strict building inspector. He's always poking around, looking for code violations, but he might also be hiding something related to the murders. Another character could be a foreign exchange student who lives in the building for a short time. She has a different cultural background and way of thinking, which could help the main characters see the case from a new angle. And finally, a homeless person who has been camping near the building could be added. He has seen a lot of comings and goings around the building and might have some valuable information about the murders.
A cyborg vampire hunter. This character could have been created specifically to hunt down Dracula and his minions. With their mechanical parts, they could have enhanced strength, speed, and the ability to analyze vampire weaknesses on the fly.
For Only Murders in the Building fan fiction, here's an idea. The murders start to follow a pattern based on an old, forgotten play that was once performed in the building. The characters have to research the play, its actors, and the events that happened during its production. Maybe there's a curse associated with the play. Another idea is that a famous detective from another era comes to visit the building and challenges our three main characters to a race to solve the murders. And finally, what if there was a virtual reality game in the building that was somehow involved in the murders, and the characters have to enter the game to find clues.
I really like Charles - Haden Savage in fanfiction. His past as an actor and his somewhat neurotic nature make for really interesting character development. He often has these great moments of self - discovery while solving mysteries.
A wise old owl that lives in the forest near the Nutcracker's world. The owl could offer advice and guidance to the Nutcracker Prince and Clara on their adventures.
A blind swordsman could be an interesting addition. He could have a unique fighting style that relies on sound and intuition, and he could become either an ally or an enemy of the Blue Eye Samurai. Another character could be a young girl who dreams of becoming a samurai herself. She could look up to the Blue Eye Samurai and follow them around, learning from their every move. And a foreign merchant who has knowledge of different weapons and fighting techniques from other lands could also be added.
A young, inexperienced wizard could be added. He could be seeking the main character's guidance and in the process bring some new magic elements into the story. Another potential character could be a fierce warrior from a far - off land, who has different combat techniques and a unique code of honor. There could also be a mysterious old hermit who has knowledge of ancient prophecies related to the main character's journey.
An old mountain man who has been living in a different part of the mountain for decades. He could be a bit of a mystery at first, with his own set of rules and traditions. Sam could meet him during one of his explorations and they could share stories of their experiences in the wilderness. The old man could also teach Sam some ancient survival techniques that have been passed down through generations.
A new character could be a super - smart girl who always outsmarts Greg in class. Another could be a mysterious janitor who seems to know a lot about the school's secrets. And perhaps a foreign exchange student who has really strange habits and becomes Greg's new friend or rival.
A young journalist could be added. He's eager to make a name for himself by getting the inside scoop on Billy the Kid. He follows Billy around, trying to interview him and in the process, gets caught up in the dangerous world of the outlaws.
Imagine a character who is a bounty hunter with a unique code of ethics. Instead of just being after the highest price, they are more interested in justice. They could get involved in the conflict between the Resistance and the First Order, sometimes helping one side and sometimes the other depending on who they believe is in the right at the moment.