Well, I think some of the characters might be really flattered. Ruby, for example, would probably be super excited to see how fans are inspired by the music in the RWBY world and create stories around it. She loves the positive energy and creativity that comes with it.
Blake could have a more introspective reaction. Since she is often deep in thought, she might see the fanfiction as a way to explore different aspects of the RWBY world that she hadn't considered before. The music in RWBY is often tied to emotions and themes, and the fanfiction might make her think about how those elements interact in new and interesting ways. She might also be interested in how the fanfiction uses music to tell a story within the story.
The music can set the mood. For example, if it's a sad song, it can intensify the emotional moments of the story. It can also foreshadow events. If a fast - paced, intense song plays, it might hint at an upcoming battle.
Music can be a form of emotional expression in these fanfictions. For the characters, it might be a way to cope with the stress of fighting Grimm. Like Yang could listen to some heavy metal - like music in Remnant to let out her anger and frustration after a tough battle.
Yang would be excited too. She's a very energetic character. She might see the fanfiction as a fun addition to the RWBY universe. If there are any action - packed parts in the fanfiction related to the music, like how a song pumps up a character before a fight, Yang would be really into it. She might even start coming up with her own ideas for similar fanfictions.
Ruby would likely have a big smile on her face. She's always positive and would be happy to see the creativity of the fans. So she'd probably be all for it.
They might have diverse reactions. Ruby could be excited and start bouncing around, loving the energetic music. Weiss might be a bit more reserved at first but then get into it. Blake could relate certain music to her own past and experiences, and Yang would probably be all about the powerful, upbeat tunes.
They might be really confused at first. Earth music is so different from the music in their world. For example, the beats and rhythms could be completely new to them. They might also be intrigued by the lyrics, especially if they touch on themes that are relevant to their own experiences in RWBY, like friendship and fighting for what's right.
One great RWBY listens to music fanfiction could be where the characters discover new music from different Remnant cultures. For example, Weiss might find some old Atlesian opera music that has a profound impact on her character development. It could show her reconnecting with her Atlesian roots and using the music as inspiration for her Glyphs.