It's hard to say. Naruto has his powerful ninjutsu like the Sage Mode and the Nine - Tails chakra. But Salem has her own dark magic and immortality. If Naruto can figure out a way to counter Salem's immortality, he could be very powerful against her. However, in the RWBY world, characters like Ruby with her silver eyes power also have the potential to be extremely strong. So it really depends on how the story is written.
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.
In some RWBY fanfictions, Naruto might save Salem by using his powerful jutsu. For example, his Shadow Clone Jutsu could be used to create distractions while he finds a way to break Salem's dark magic. His Rasengan might also be able to counteract some of the negative energy she emits.
Well, loyalty is a big one, as Tyrian is very devoted to Salem. Power dynamics are also common, like how Salem's power over Tyrian affects their interactions. The theme of manipulation can be present too. Salem is a very manipulative character, and in fanfiction, this can be explored in relation to Tyrian. There could be themes of trust and betrayal as well. For instance, would Tyrian ever betray Salem, or vice versa? And sometimes there are themes of the unknown or the mystery of their relationship. Writers might try to fill in the gaps of what we don't know about how they truly feel about each other.
There are definitely some out there. Some might explore the dark and twisted nature of their possible relationship within the context of the RWBY universe. However, the quality can vary a lot. It's important to read reviews or summaries before diving into a particular fanfiction to make sure it meets your expectations.
Power is a common theme. Often, the OC either gains power from Salem or has to deal with Salem's overwhelming power. Another theme is loyalty. The OC may struggle with being loyal to Salem or may have their own sense of loyalty that conflicts with Salem's goals.
One possible scenario is that Naruto uses his Sage Mode to sense Salem's true nature and the source of her power. Then he can target that source and use his unique techniques to neutralize it. Another could be that he forms an unexpected bond with Salem, similar to the bonds he formed with his enemies in his own story. Through this bond, he gradually changes her perspective and saves her from her path of destruction.
Fanfiction writers blend the universes by creating new storylines. They might have Naruto end up in RWBY's world due to some magical accident. Once there, he has to deal with Salem's threat. The RWBY characters are initially skeptical of Naruto but soon come to respect his abilities. The different cultures of the universes are also merged. The shinobi way of life from Naruto can be seen rubbing off on the RWBY characters, and the technology and magic of RWBY can be something new and exciting for Naruto. Salem, as a powerful antagonist, adds an extra layer of danger and mystery to the blend of these universes.
There's a fanfiction called 'RWBY and Naruto: A Crossover of Power'. In this, the characters from RWBY and Naruto come together to face a common threat. For example, Ruby's scythe skills combined with Naruto's combat experience make for some exciting fight scenes. Also, the story might explore how the different power systems, like semblances and chakra, interact with each other.
Fanfiction about Ozma and Salem in RWBY can be quite creative. Some might focus on their love story that turned so sour. It could be about how their initial love was pure but got corrupted over time due to various factors like the power they both held or the interference of others. Others may explore their powers in unique ways. For instance, how Ozma's reincarnation magic could be used differently or how Salem's control over Grimm could be more nuanced. There are countless possibilities for writers to play with in the context of these two characters in RWBY fanfiction.