One idea could be Ruby trying to understand Salem's motives beyond just destruction. Maybe she discovers that Salem has a tragic past that led her to this path and Ruby attempts to find a way to redeem her. Another plot could involve Salem targeting Ruby specifically because of her silver - eyed powers and Ruby having to outwit Salem in a series of battles.
Maybe Salem's daughter has unique powers that are different from her mother's. She might struggle to come to terms with these powers and whether to use them for good or evil. For example, she could have the power to heal, which is the opposite of Salem's destructive nature, and she has to decide if she'll use it to counter her mother's actions.
One idea could be exploring their past relationship in more detail. Maybe a time when they first met and how their initial trust or distrust formed.
One interesting fanfiction could be where Ruby has to face Salem alone in a battle of wits and strength. In this story, Ruby might discover a new power within herself to counter Salem's dark magic.
One plot idea could be that Ruby discovers a hidden connection between her Silver - eyed powers and Ozma's ancient magic. Maybe she has visions that lead her to an old relic related to Ozma. Another could be that they team up to fight a new, powerful Grimm threat that is immune to normal Huntsman attacks, but Ruby's unique abilities combined with Ozma's knowledge can defeat it.
One plot idea could be Ruby and Winter teaming up for a special mission. Maybe they have to infiltrate an enemy stronghold. Ruby's speed and Crescent Rose could be combined with Winter's ice powers and combat skills for some epic fight scenes.
One plot idea could be Qrow training Ruby in some special combat techniques that are unique to his own fighting style. This would allow Ruby to gain new skills and also strengthen their bond as family members.
A possible plot for a fanfiction about Whitley and Ruby in RWBY could be that they are both chosen for a special task by Ozpin (or his successor). They are the least likely pair to be chosen together, but as they work on the task, they find out that they complement each other well. Whitley's knowledge of Atlas society and technology, combined with Ruby's combat skills and leadership, make them a formidable team. Along the way, they might face challenges from within the group that doesn't believe in their partnership, but they prove everyone wrong by achieving their goals successfully.
Another plot could involve Ruby and Arslan getting into a friendly competition. They could be competing in a tournament within the RWBY universe. This would show their different fighting styles and how they learn from each other during the competition. They might start off as rivals but end up as good friends.
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.
Perhaps Salem discovers a way to use Naruto's chakra for her own evil purposes. So, Naruto has to find a way to stop her while also dealing with the new and unfamiliar world of RWBY. He might learn some new skills from the RWBY characters along the way.