Another common theme might be the contrast between Ruby's overprotective side and her normal, more carefree self. In the fanfiction, the author could play with this contrast, showing how Ruby is usually a positive and enthusiastic person, but when it comes to the safety of her team, she becomes a completely different, more intense person. This can add depth to her character and also create interesting storylines within the fanfiction.
One possible fanfiction could be where Ruby is overprotective of her team during a dangerous mission. Maybe she constantly checks on their safety, making sure they don't take unnecessary risks. For example, when they are facing Grimm, she might be extra vigilant about any threats towards Weiss, Blake, and Yang, and jump in to protect them even before they realize the danger.
One common theme is loyalty. The overprotective sister is often extremely loyal to her sibling, willing to go to great lengths to keep them safe. For example, she might put herself in danger without hesitation.
One common theme is leadership. Ruby is a team leader in RWBY, and many fanfictions explore how she grows into that role, like dealing with difficult decisions and inspiring her teammates. For example, in some fanfictions, she has to lead her team through a very dangerous mission where every decision matters.
One common theme is family. Since Raven is Ruby's mother, a lot of fanfictions explore their relationship in that context. It could be about Ruby trying to understand her mother better or Raven coming to terms with being a mother.
One common theme could be the exploration of Ruby's character growth in the face of abuse. Maybe she overcomes it and becomes stronger. Another theme might be how her friends react to her situation, whether they support her fully or struggle to understand what she's been through.
One common theme is Ruby's struggle with her new, darker powers as the Reaper. Writers often explore how she copes with the changes and the potential isolation it might bring. For example, she might have to hide her new form from her friends at first.
Character development is also frequently seen. Writers might explore how Ruby and Blake change over time, perhaps in response to the events in the RWBY universe. For example, how Blake deals with her past and how Ruby matures as a leader. Additionally, adventure themes are common, where they go on quests together, facing new enemies and exploring new places.
Another theme could be acceptance. How her friends and the people around her accept and support her. It might show the growth of relationships within the RWBY universe as they learn more about Ruby's autism. There could also be themes related to Ruby's special interests within the RWBY world, like her weapon or her combat skills, and how her autism influences those interests.
The exploration of their backstories together is also a theme. Writers may create scenarios where Ruby and Cinder's pasts are somehow intertwined, perhaps revealing secrets that change their relationship in the RWBY universe.
One common theme is self - discovery. Ruby often has to figure out who she is in the context of her new family or situation. For example, in many of these fanfictions, she might realize new strengths or weaknesses she didn't know she had.