One possible reason could be a difference in combat strategies. Maybe Ruby has a very specific and aggressive way of approaching battles, and her team is being more cautious or hesitant. For example, if they keep refusing to follow her lead during a fight against a powerful Grimm, it could make her mad.
It could be due to a lack of communication. Her team might be making decisions without consulting her first. Suppose they take on a mission without Ruby's knowledge that she feels is too dangerous or not in line with their overall goals. This could lead to her being angry at them.
In some fanfictions, Naruto could be mad at Team 7 if there was a new member added and he felt replaced. He has a deep bond with Sasuke, Sakura, and Kakashi, and any disruption to that dynamic might lead to anger. Also, if the team made a decision without consulting him, like choosing a mission target without his input, that could be a cause for his anger.
One possible reason could be that she loses inspiration. Maybe she has explored all the ideas she initially had for her fanfiction and can't come up with new and exciting storylines. Another reason might be lack of time. If she gets involved in more important or urgent matters in the RWBY universe, she simply doesn't have the hours to sit down and write fanfiction anymore. Also, she could face criticism from others which makes her lose confidence in her writing and decide to give it up.
She might run away because of a conflict with her friends or team members. Maybe there was a misunderstanding or a disagreement that she couldn't resolve at that moment, and running away seemed like the best way to avoid further confrontation.
With Yang, their relationship would likely be less of a sisterly, protective one. Since Goodwitch would be in a parenting role, Ruby might not rely on Yang as much for protection. Yang might also see Ruby as more independent and grown - up, which could lead to a more equal friendship.
Maybe Snape made a snide comment about Hermione's intelligence or her Muggle - born status. Snape has a rather acerbic tongue, and if he said something derogatory about Hermione's abilities or her heritage, she would surely be furious. After all, Hermione works extremely hard to prove herself in the wizarding world and any attack on her intelligence or background would be a big blow.
In fanfiction, the neglect of Ruby by Team RWBY could be due to a trend. Writers often follow what seems popular at the moment. If currently, other characters in Team RWBY are more 'in vogue' for creating drama or romance scenarios, Ruby might be sidelined. Additionally, her relatively straightforward and heroic nature might be seen as less complex to write about compared to characters with more internal conflicts like Blake or Weiss.
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.
Character relationships are a key element. For example, Ruby's relationship with Yang as sisters but also as teammates is often explored. Their interactions can range from playful banter to serious moments of support.
One possible reason could be to explore different character dynamics. By changing their age order, fanfiction writers can create new storylines. For instance, it can lead to a different kind of sisterly bond between them.
When Ruby becomes a demon in this fanfiction, her relationships with her team are bound to change drastically. Her new form and the powers that come with it could make her more unpredictable. Her team members like Pyrrha (if she was still around) might see her as a danger to the team. This transformation could lead to a lot of mistrust and conflict within the group as they struggle to come to terms with Ruby's new state.