One common theme could be Ruby facing some sort of emotional coldness or isolation. Maybe she's been through a tough event and has withdrawn from her friends.
Another theme might be related to Ruby's powers being affected in a 'cold' way. For example, her powers could become less effective or have some sort of icy side - effect. This could create interesting storylines where she has to adapt and overcome. In addition, the theme of friendship in the face of this 'cold' change in Ruby could also be explored. How her friends react to this new, colder Ruby and try to bring back the old her.
Often, there can be a theme of Ruby being in a cold, unforgiving environment, either literally or metaphorically. This could be a new world she's thrust into, or a situation within the RWBY universe that has turned cold and hostile. Her journey to survive and thrive in such an environment can be a central theme in many 'rwby cold ruby' fanfictions.
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.
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.
A prevalent theme is the exploration of their relationship. This can range from a deep platonic bond to something more romantic in some fanfictions. Also, the theme of loyalty is common. They are loyal to each other as members of their team, and fanfictions will often have situations where this loyalty is tested, like when one of them is in danger and the other has to make a choice to save them.
In Ruby mourning fanfictions, a significant theme is the struggle to move forward. Ruby is stuck in her grief, and the story is about her trying to break free from it. Another common theme is the change in relationships. Her relationships with other characters are often affected by her mourning, either they become closer as they try to support her or they drift apart because she pushes them away.
Another theme is discovery. Ruby discovers new things about herself, her powers, or the world around her through her interactions with Kali. And Kali might also discover new aspects of the younger generation's way of thinking and fighting through Ruby. This mutual discovery helps to drive the plot in many of these fanfictions.
One common theme is identity. Ruby has to figure out how being a princess fits into who she is, as she's always seen herself as a Huntress. Another theme is responsibility. With princess status comes new duties, like ruling or representing a kingdom. Also, friendship often plays a role. Her friends might have to adjust to her new status, and she might rely on them in her new royal life.
One common theme is self - discovery. When Ruby is alone, she has time to reflect on herself, her powers, and her purpose. For example, she might realize new aspects of her Semblance or her role as a Huntress.
Friendship is also a common theme. Despite their differences in age and experience, Ruby and Goodwitch can form a unique friendship in fanfictions. This friendship can be tested in various ways, like facing a powerful enemy together or having a misunderstanding that they need to overcome. These stories about their friendship add depth to their characters and make the RWBY universe feel more alive and relatable.