A possible plot twist is that a character from RWBY gets influenced by a particular hero or villain from the WW2 documentaries. Let's say Ruby sees the courage of a WW2 soldier and tries to adapt that unwavering determination in her fight against the Grimm. Or perhaps a villain in RWBY is inspired by a dictator in WW2 and tries to take over their own world in a similar way. This could lead to a whole new set of conflicts and challenges for the RWBY team.
Yang would likely be angry. She has a strong sense of justice, and seeing the atrocities in WW2 would make her want to take action against any form of oppression. The RWBY characters as a whole would probably be horrified. They are used to fighting Grimm, which are more like mindless monsters, but seeing human - on - human violence on such a scale would be a new and difficult concept for them. They might start to question the nature of humanity more deeply and wonder how they can ensure that their own world doesn't descend into such chaos.
One cool plot twist could be that in one of the multiverse scenarios, their enemies are actually their allies. This would completely turn their understanding of good and evil on its head and force them to reevaluate their relationships. It could lead to some really intense character development as they try to figure out what this means for their own world.
One possible plot twist could be that the drunk marriage was part of an enemy's scheme. Maybe Salem or her minions manipulated the situation to create chaos within the RWBY team. For example, they spiked the drinks at a party, leading two characters to get married. Then, when the characters realize what has happened, they have to deal with the legal and emotional consequences while also trying to figure out who set them up.
One possible plot twist could be that the future they see is not the real future but a fabricated one by the mastermind to manipulate them. This would create a lot of confusion and mistrust among the class members.
Another interesting plot twist might be that the White Fang, instead of being a completely antagonistic force, has a group within it that wants to work with the Huntsmen and Huntresses. They realize that their violent methods are not achieving their long - term goals and they approach Team RWBY and the others to form an alliance. This would completely change the dynamics between the characters and the story's view on the Faunus - human conflict.
Another plot twist could be that Papyrus realizes the fight is all an illusion. In the fanfiction, he might see through some sort of magic or mind - control that was making Sans fight. So, he then has to figure out how to break the illusion and save Sans from this false battle.
One interesting plot twist could be when a character from Burgess who was thought to be just an ordinary person turns out to have a hidden power that is crucial in helping the Guardians. For example, a young girl might discover she can control ice like Jack Frost, which was unexpected and changes the whole dynamic of their fight against the bad guys.
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 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.
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.