In a 'henceforward rwby fanfic', a new character could be a young boy from a nomadic tribe in Remnant. His semblance is the ability to sense danger from miles away, which has kept his tribe safe for generations. He could join the RWBY gang on their adventures, bringing with him a different perspective on the world. Another potential character is a female knight from an ancient order in Atlas. She has a very strict code of honor and her semblance is the ability to make her armor impenetrable for a short period. Also, a character from a hidden underground city in Remnant could be introduced. This character has a semblance that allows them to phase through solid objects and could provide some interesting plot twists in the fanfic.
A character could be a mysterious guide who knows all about this 'another world'. He or she could be an old hermit who has lived in this world for a long time and has unique powers related to the world's natural elements.
There could be a group of orphans who have banded together and developed their own unique style of ninjutsu out of necessity. These orphans could add a new dimension to the story as they struggle to survive in a world full of powerful ninjas while also trying to find their place in it.
A new Akatsuki member, a young and powerful ninja who has a personal vendetta against Naruto. Their clashes could add a lot of drama and action to the fanfic.
A species - specific character like a Chiss bounty hunter. The Chiss are known for their intelligence and strategic thinking. This bounty hunter could be on a mission to capture a high - profile target in the Star Wars Visions universe. They would use their unique Chiss abilities, such as their natural aptitude for tactics, to outwit their opponents.
One possibility is a young girl who has the ability to control light in a way different from Ruby's speed. She could be a street urchin who has been surviving on her own in the slums of a major city in Remnant. When she meets the RWBY team, she initially distrusts them but eventually becomes an important part of their group. Also, a grizzled old veteran of many battles against Grimm could be added. He could be a mentor figure, teaching the RWBY characters new combat techniques and sharing his wisdom about the history of Remnant and the Grimm.
A young and talented artist could be a new character. The empress could commission the artist to create a portrait or some art for the palace, and in the process, a unique friendship or a complex relationship could develop. The artist could also be a source of inspiration for the empress in different ways.
Ruby is always a great choice. Her journey from a young huntress - in - training to a more experienced leader provides a lot of material for fanfiction. You can explore her growth, her relationships with her team, and how she copes with the increasing challenges.
There could be a new neighbor in Jenna's apartment building. A quirky artist who inspires Jenna in new ways, either in her personal life or her career at the magazine.
A skilled samurai girl from the Iron Country. She could be a master of a unique sword - fighting style. Maybe she initially distrusts Naruto because of the differences between ninja and samurai, but later becomes his ally and friend.
A mysterious detective from another city who has a different approach to solving crimes compared to Sherlock. This character could initially be at odds with Molly but later become an ally. Another could be a reclusive scientist who has some dark secrets related to the cases Molly is involved in. There might also be a street - smart informant who has connections in the underworld and provides Molly with valuable information, but at a price.