Well, it could be about Si somehow getting transported into the RWBY world and gradually taking on the characteristics and powers of Salem. Maybe Si starts to influence the existing power dynamics in the RWBY universe, causing chaos among the various factions like the Huntsmen and the Grimm. For example, Si could start to manipulate some of the characters, using knowledge from the real world to outwit them and further Salem's goals, even if it's unconsciously at first.
In the 'Si becomes Salem' RWBY fanfiction, it might be that Si is a reincarnation of Salem. Si could start to remember Salem's past lives and her vendetta against the gods. This could cause Si to question their own identity and purpose. They might also encounter Ruby and her team, and there could be a complex relationship where the team tries to figure out if Si can be redeemed or if they are too far gone into becoming Salem.
Perhaps in this fanfiction, Si becomes Salem as a result of a powerful magical experiment gone wrong. Si might then have to deal with Salem's memories and desires. Since Salem wants to destroy humanity in RWBY, Si could struggle with these newfound urges. This could lead to a story where Si tries to resist Salem's evil nature while also being hunted by the good guys who think Si is fully Salem now.
Blake Belladonna would also make a great main character. Given her own past with the White Fang and her knowledge of different power structures, she could try to understand what's happening to Si. And Yang Xiao Long, with her powerful fighting skills and protective nature towards her sister Ruby, would likely get involved. She might be the one who has the most direct confrontations with Si as they turn into Salem, trying to knock some sense into them.
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.
One plot idea could be that Si is a new student at Beacon Academy. They are in awe of Ruby and her skills. So, they start to follow Ruby around to learn from her. Along the way, they get involved in Ruby's adventures against the Grimm, and their own abilities start to develop as they face various challenges side by side with Ruby.
The challenges are numerous. First, Salem has a long - standing enmity with Ozpin and many others. The SI would need to navigate those relationships. Also, Salem has a certain ideology that has driven her actions for centuries. Changing that mindset would be a huge task. And don't forget about her Grimm - related powers. Understanding and using them in a positive way is no easy feat.
Well, if someone reincarnates into Salem, they'd likely face a whole lot of moral dilemmas. Salem is a complex and often villainous character in RWBY. They might try to change her path, but they'd have to deal with her existing power and all the enemies she's made. It could also lead to some really interesting interactions with the other characters like Ozpin, who has a long - standing feud with Salem.
One possible plot twist could be that RWBY initially believes Salem's motives are good. Since she raised them, they might be blind to her true evil nature at first. For example, Salem could have presented herself as a protector against some other greater threat, making RWBY question their newfound allies when they start to oppose Salem.
Well, one way is through friendship. If the SI befriends Salem and the characters around her, they can start to influence her with positive values. For example, by sharing stories of hope and unity from their own world.
Well, they'd first have to deal with Salem's powers. It's not easy to suddenly have such great and dark powers. They might struggle to control them at first. For example, Salem can manipulate Grimm, and the reincarnated 'Si' might accidentally summon Grimm when they don't mean to, causing chaos in the areas around them.
Well, it could be about Ruby facing some kind of extreme situation or transformation that turns her into a more 'red' version of herself. Maybe she discovers a new power within her that has a red hue and she has to learn to control it. This could lead to her having a different fighting style and new relationships with her teammates as they adjust to this new Ruby.
Well, one possibility is that Ruby has to face many challenges to become the Fall Maiden. Maybe she has to fight against other powerful foes who also want the power. She might struggle with the new responsibilities and powers that come with being the Fall Maiden.