A scientist who is an expert on alien plants. He could be brought in to study the plant and try to find a way to control it.
Superman could be an interesting addition. His superpowers and moral stance would contrast and interact with Batman in many ways, creating a lot of drama and action.
A young stargazer from Earth could be a new character. This character could be someone who has always been fascinated by the stars and dreams of traveling to other planets. When the Little Prince lands on Earth again, they meet and the stargazer becomes his guide on Earth, showing him all the new things that have happened since his last visit. Another potential character could be a talking moonbeam. It could offer the Little Prince advice and wisdom, as well as some magical abilities to help him on his journey.
The main characters include Seymour, a young and somewhat naive florist. He is the one who discovers and nurtures the mysterious plant. Audrey, a sweet girl who works with Seymour and is the object of his affection. And Audrey II, the plant which is not only a character but also the main antagonist in the story. It has a personality of its own and constantly demands to be fed, driving the whole story forward with its bloodthirsty nature.
The main character is the florist who owns the shop where the strange plant appears. And of course, the plant Audrey II is also like a main character in a sense as it drives much of the action.
An old - fashioned Pokemon breeder who has a deep connection with the traditional ways of raising Pokemon. They could provide the main characters with valuable advice on how to make their Pokemon stronger and healthier. However, they might also be a bit stubborn about sticking to the old ways and this could cause some conflicts with the more modern - thinking characters in the fanfic.
There could also be a group of street - smart kids who befriend the Baudelaires. They have their own set of skills and stories, and together they can form a sort of alliance to protect their neighborhood from any potential threats. These new characters would bring in fresh perspectives and interactions for the existing characters in the fanfic.
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.
You could add a young and inexperienced vault hunter who is eager to make a name for themselves. They might start off as a bit of a nuisance to the more experienced characters but gradually prove their worth. There could also be a mysterious merchant who is not what they seem. They might have a hidden agenda and be involved in some sort of illegal trading that could have a big impact on the Borderlands economy.
A nomadic vampire with a completely different set of values compared to the Cullens. He could be more in tune with his animalistic side and not believe in the Cullens' way of trying to blend in with humans. His presence could cause conflict within the vampire community in Forks and also attract the attention of the werewolves.
A young, adventurous boy from a neighboring town. He could be quite different from the characters Little Miss Marker is used to. He's full of energy and new ideas, and together they could get into all sorts of escapades, like exploring an old, abandoned castle.