For the RVB characters in the RWBY world, you can have them develop new skills related to Aura and Semblances. For example, Tucker could discover his Semblance is something like enhanced swordsmanship. And they could also develop in terms of their understanding of the RWBY universe's values.
Well, a cool concept in RWBY and RVB crossover fanfic is the technology exchange. RVB has advanced military tech, and RWBY has Dust - based technology. Imagine a situation where the teams in RWBY start using some of RVB's weapon systems or vice versa. Also, the different team dynamics could lead to some interesting storylines. The tight - knit teams in RWBY might learn from the more chaotic but effective teamwork in RVB.
A great idea for an RVB RWBY crossover fanfic could be a tournament - style story. Characters from both universes are forced to participate in a huge tournament. This would allow for a lot of different match - ups between the characters. The Reds and Blues' comical and sometimes unorthodox fighting styles would contrast with the more refined and trained fighting styles of RWBY characters. It could also lead to some interesting friendships or rivalries forming during the tournament.
They'd likely be confused at first. The settings and characters of RVB are so different from their own. But Ruby might get excited about new combat ideas. She loves new ways to fight. Yang would probably laugh at any funny dialogues. Weiss might be a bit dismissive as it's not the high - class literature she prefers. Blake could be the most open - minded, seeing potential in the different storytelling.
One challenge is character integration. The characters from RVB and RWBY have very different personalities and backstories. For example, the Reds and Blues are often comical and more laid - back compared to the RWBY characters who are more on a mission to save their world. So, making them interact in a believable way can be tough.
There's a crossover fic called 'Colors of Combat'. In this story, the Reds and Blues find themselves in the RWBY universe and have to adapt to the new rules and powers there. It has great character development as they learn from the RWBY characters and vice versa. The story also has some really cool fight scenes that blend the combat styles of both series.
Ruby and Church could be an interesting pairing. Ruby is young and idealistic, while Church is often sarcastic and has a more jaded view. Their interactions could be really fun to read. Another would be Weiss and Tucker. Weiss is from a high - society background and Tucker is, well, Tucker. The contrast in their personalities and upbringing would make for an engaging story.
A good way to find quality 'rvb vs rwby fanfic' is to follow the works of well - known fanfic authors in either the RVB or RWBY fandoms. If they have written crossovers before, chances are their 'rvb vs rwby' works will also be well - written. You can usually find lists of popular authors on the aforementioned fanfiction websites. Once you find an author you like, you can explore their other works as well.
There's also 'The Battle Beyond' which focuses more on the strategic aspects of the RWBY and RVB characters coming together. It shows how they use their unique abilities in combination to overcome challenges. It's a great read if you like to see how different power sets interact.
For the FMA characters in the OHSHC world, you can show how they adapt to the new social norms. Edward, for instance, might initially be frustrated with the elaborate social games in OHSHC but gradually learn to play along. You can also focus on how their goals change. Maybe they start off trying to find a way back to their own world but then become invested in the problems of the OHSHC characters. For the OHSHC characters in the FMA world, their charm could be used in different ways. Tamaki could try to use his charm to negotiate with the military in FMA.
With Jack Frost, his character can be developed by showing his reaction to the dragons. He might be fascinated by them at first but also a bit scared. His relationship with Toothless could be a key part. Maybe Toothless doesn't trust him immediately, and Jack has to earn that trust. This would show his determination and his ability to connect with different beings.