Jaune is probably the protagonist around whom the story revolves. As for the Maidens, they are likely characters with special powers. They could be a group of female characters with different personalities and abilities related to elements like fire, water, earth and air. Their interactions with Jaune would be a major part of the story, as they work together or face conflicts within the story's universe.
The main character is Jaune. He might be on a quest or have a certain goal related to the Maidens. The Maidens themselves are also main characters. They could be characters who have been chosen or born with special Maiden powers. They may come from different backgrounds, and their destinies are somehow intertwined with Jaune's in this fanfiction.
One idea could be Jaune's journey in training the Maidens and how he helps them unlock their full potential. Maybe he discovers a new form of combat that combines their Maiden powers with his own skills.
The knight would obviously be one of the main characters. He could be a new character created specifically for the fanfic, or perhaps a reimagined version of an existing RWBY character with knight - like qualities. The maidens would also be main characters. They could be based on the RWBY girls, or entirely new characters with unique abilities and personalities.
The RWBY team - Ruby, Weiss, Blake, and Yang - could also be important characters in the 'rwby four maidens fanfic'. They might interact with the maidens, either as allies or in some cases, having to resolve conflicts. For example, if there is a misunderstanding about the maidens' powers or intentions, the RWBY team would be there to figure things out.
Well, Jaune in RWBY fanfiction can vary a lot. Sometimes he's the underdog who overcomes huge challenges, and other times he might have unique powers or a special backstory.
Obviously, Jaune would be one of the main characters. And considering the RWBY series, Ruby, Weiss, Blake, and Yang are likely to be involved as well. They are the main protagonists of RWBY and often interact with Jaune. So it's possible that one of them could be the recipient of Jaune's nightly visit.
Jaune is the main character who is taken by Raven. He's the one who will be experiencing all the strange and funny things that Raven puts him through. Raven is the other main character, the one who initiates the whole situation. However, depending on how the fanfiction is written, there could be side characters like Yang who might come looking for Jaune and end up in some humorous encounters with Raven as well.
The knight could be developed by showing his code of honor. For example, in every battle he faces, he adheres to a strict set of rules. His backstory might be gradually revealed, like he was once a soldier in a great war and now he feels a sense of duty to protect the maidens. The maidens, on the other hand, could be developed through their interactions with the knight. Maybe one maiden is initially shy but as she spends more time with the knight, she becomes more confident in her abilities.
Ruby would most likely be involved. She's the leader of Team RWBY and has a strong sense of justice. She would be determined to find Jaune no matter what. Weiss could also be involved as she has the resources and skills to help in the search. Her family's influence and her own combat abilities would be useful.
Not having read 'the maidens a novel', it's difficult to determine the main characters. But it's reasonable to think that the maidens themselves are the central focus. There could be different types of maidens, for example, a bold and adventurous maiden, a shy and reserved one, etc. And they may interact with characters such as a wise old woman who gives them advice, or a young man who causes some sort of conflict or romance in their lives.
It could be Cinder Fall. She's always been a major villain in RWBY. She might be the one who arranges for Blake and Jaune to be banished as part of her evil plan to gain more power or cause chaos in the world of Remnant.