One interesting plot twist could be that Soldier 76's time - traveling abilities (if we assume some extended lore) bring him to the RWBY universe during a crucial moment in a battle. His military tactics and advanced weaponry completely change the tide of the fight. Another could be that in the crossover, Soldier 76 has some sort of connection to one of the RWBY characters' pasts, like he was involved in an event that shaped their family history. And a third plot twist might be that his healing abilities become a key factor in saving a major RWBY character from a near - fatal injury, leading to a new alliance between him and the RWBY team.
A possible plot twist is that Soldier 76 discovers a parallel between his own world's problems and the Grimm situation in RWBY. He then tries to implement the solutions from his world to deal with the Grimm, but they backfire in unexpected ways. For example, his high - tech barricades attract a new type of Grimm that is attracted to technology. Another twist could be that a RWBY character discovers Soldier 76's weakness, which is something completely different from what is expected in his own universe. And finally, a plot twist could be that Soldier 76's visor, which has some special functions in his own lore, starts to show visions of the future of the RWBY world, which he then has to decide whether to act on or not.
One interesting plot twist could be the Keyblade wielders finding themselves in the world of Remnant. They might initially be confused by the Grimm and the Huntsmen system. For example, Sora could mistake a Grimm for a Heartless at first, but then realize it's a whole different kind of threat. Another could be Ruby and her team getting access to the power of the Keyblade. Ruby's scythe skills combined with Keyblade magic would make for an incredibly powerful combination. And perhaps a plot twist where the villains from both universes team up. Salem could see the power of the Heartless and use them to her advantage, while Xehanort might be interested in the power of the Maidens in RWBY.
Sure. One interesting plot twist could be that the five nights are actually a test set up by Ozpin to see how the characters will react under extreme stress. But as the nights progress, things go wrong and real threats emerge that were not part of the original test plan. This would add an extra layer of mystery and danger to the fanfiction, and force the RWBY characters to adapt quickly to new and unexpected situations.
One exciting plot twist could be Spider - Man's web - slinging abilities affecting the Grimm in RWBY. Maybe his webs are able to hold the Grimm in a way that the Huntsmen and Huntresses in RWBY have never seen before. This could change the way battles are fought. Another could be that Spider - Man has to adapt to the world of Remnant, where the rules of physics and combat are different from his own world. For example, he has to figure out how to deal with Dust, the energy source in RWBY, and incorporate it into his fighting style.
One interesting plot twist could be the alchemy of the Fullmetal Alchemist world interacting with the Dust in RWBY. For example, maybe an alchemist discovers a way to transmute Dust into something completely new and unexpected, which throws the balance of power in Remnant (RWBY's world) into chaos. Another could be a character from RWBY somehow getting involved in the Philosopher's Stone plot of Fullmetal Alchemist, leading to a race between different factions in both worlds to either obtain or destroy it.
A really interesting plot twist in 'Magic and RWBY: The Unexpected Alliance' is when the villains of RWBY team up with some of the darker forces in the Magic the Gathering universe. It makes the heroes reevaluate their strategies and forces them to find new allies among the Magic the Gathering characters.
One possible plot could be that the characters from RWBY end up in the Persona universe and have to learn how to use Personas to fight the Shadows. For example, Ruby could discover her Persona is related to her speed and scythe skills, and she uses it to quickly dispatch enemies. The team would also have to deal with the social aspects of the Persona world, like building relationships to strengthen their Personas.
One possible plot could be that the Autobots and Decepticons end up on Remnant. The RWBY teams initially mistake them for new types of Grimm. But then they realize they are sentient machines. They team up with the Autobots to fight off the Decepticons who are trying to mine Remnant for its resources.
A cool plot might involve a dark force that is affecting both the RWBY world and Kirby's world. This force is causing strange things to happen, like Grimm starting to appear in Dream Land and some of Kirby's enemies showing up in Remnant. Ruby, Weiss, Blake, and Yang meet Kirby, and they initially don't understand him but soon realize his power. They work together to find the source of this dark force. Kirby uses his inhale ability to help them gather information by sucking up some of the smaller Grimm and enemies to learn more about what's going on.
A possible plot is that the RWBY characters end up in New York. Ruby, with her speed and scythe skills, is initially mistaken for a threat by Spiderman. But when they realize they are both on the side of good, they join forces. Weiss could use her glyphs in new and creative ways in the urban environment, Blake's stealth and acrobatic skills could be put to great use, and Yang's strength would be a valuable asset. Together they take on a criminal organization that has somehow gotten hold of some Dust and is using it for evil purposes.
Another plot could be that an evil force in the RWBY universe discovers the existence of the Omnitrix from another dimension. They manage to create a device to pull Ben and the Omnitrix into their world. Ben has to adapt quickly to this new world while Team RWBY, who are initially suspicious of him, realizes that he could be an ally against this new threat. They join forces, with Ben using his alien forms in creative ways to combat the Grimm and the evil force's minions.