If Ruby joins Salem in the fanfiction, it could be a very dark turn for Ruby. Salem might manipulate Ruby into believing that her methods are the only way to bring about a new order. However, Ruby's friends would never give up on her. They would try to rescue her, and in the process, Ruby might have a change of heart and turn against Salem, leading to an epic showdown.
The other characters would be shocked. Weiss would probably be the first to try and figure out what's wrong with Ruby. Blake would be worried about Ruby losing her way, and Yang would be furious. Yang might even go on a solo mission to bring Ruby back, not fully trusting the rest of the team to handle it delicately. The rest of the characters like Jaune and Nora would also be in disbelief and would start planning ways to rescue Ruby.
If Ruby joins Roman in the fanfiction, it might start with Ruby being tricked by Roman. He could pretend to have some information that Ruby desperately needs, like the location of a powerful relic that is about to be used for evil. Once she's with him, she realizes that his ways are completely different from hers. However, she decides to stay for a while to gather more intel. During this time, she has to constantly resist his attempts to make her more like him in terms of being less rule - bound.
Another thing that could occur is a change in the relationships within the RWBY world. If 'Si' reincarnated into Salem, they would have pre - existing relationships with all the characters that Salem had interacted with. This could lead to some very interesting dynamics. For instance, Cinder, who was once Salem's subordinate, might find herself in a very different position. The reincarnated 'Si' could try to reform Cinder, seeing potential for good in her rather than using her as a tool for evil as Salem did.
He might have a bit of a culture shock at first. The world of RWBY is quite different from the Hidden Leaf Village. But his determination would fit right in with Team RWBY's own strong - willed members. He could teach them about chakra, and in return, learn about Dust. And his rasengan could be a very powerful weapon against the enemies in RWBY.
In this fanfiction, Ruby might initially be in shock or fear upon meeting Adam. Given their opposing stances in the RWBY universe, there could be a tense stand - off. Ruby, being the hero - like character she is, might try to reason with Adam, hoping to sway him from his more violent and extreme views.
If Ruby becomes a Grimm in RWBY, it would be a total chaos. Her friends would be shocked and confused. They might initially try to save her, thinking there's still a chance to reverse the transformation. But she, as a Grimm, would likely have new instincts and powers that are contrary to her former self. Her combat style could change completely, and she might become a threat to those she once protected.
Well, one possibility is that Ruby could learn some ancient secrets about the world of Remnant from the two brothers. Maybe they would bestow upon her a new power or weapon upgrade.
The storyline could be extremely dark. Ruby, being raised by Salem, might be trained to oppose the Huntsmen and Huntresses. She could have a completely different view of the world, seeing the kingdoms as the 'bad guys' and Salem's side as the 'righteous'. Her relationships with her original friends would be in shambles as she would be on the opposing side. For example, her relationship with Weiss would be non - existent as they are on different moral spectra.
Perhaps Salem starts to change her ways because of her love for Ruby. She might begin to question her long - held beliefs and actions, which could lead to a lot of drama and conflict within the story. For example, her followers might not understand her new attitude.
One possible plot could be Ruby Rose trying to understand Salem's motives. Maybe Ruby, with her pure heart, believes there's a chance to redeem Salem. She could engage in a series of intense conversations with Salem, where Ruby tries to appeal to any good that might still be in her. This would be a great exploration of the themes of good versus evil and redemption.