Another possibility is that Captain America's values clash with some of the more morally grey areas in the RWBY universe. This could lead to interesting character development as he tries to uphold his own principles while also understanding the different ways things work in Remnant. He could even inspire some of the RWBY characters to think more about justice and fairness in a different light.
Perhaps in the fanfic, Captain America's shield could be modified with Dust technology in the RWBY world. He might also have to adjust to the different fighting styles and powers of the RWBY characters. For example, learning about Aura and Semblances and how they can be used in combination with his own abilities in combat.
One idea could be that Captain America is somehow transported to the RWBY universe. He could team up with Team RWBY to fight against the Grimm. His shield would be a unique weapon in that world, and his leadership and combat skills would be highly valuable.
A third concept could be that a magical object from the Harry Potter world, like the time - turner, is found in the Marvel universe. Captain America and the Avengers have to figure out how to use it. Meanwhile, Harry and his friends are searching for the time - turner in their world too. Eventually, their paths cross as they both try to understand the power of this object.
One idea could be a time - travel fanfic where Captain Marvel and Captain America team up in a different era. Maybe they end up in the 1920s and have to deal with a Hydra - like threat that's starting to form early. Another could be a fanfic where they swap powers for a day and have to learn to adapt to each other's abilities. For example, Captain America trying to control Captain Marvel's photon blasts and Captain Marvel having to rely on just her combat skills like Cap usually does.
He could be a mentor figure. Captain America has a wealth of combat experience and strong moral values. He could train the RWBY characters, especially in hand - to - hand combat and strategy. His presence would add a new dynamic to the Beacon Academy training sessions.
One idea could be a story where Naruto is transported to the DC universe and teams up with Captain America. They could fight against a common enemy like Darkseid. Naruto's unique jutsu and Captain America's combat skills would make for an interesting combination.
One idea could be a story where Captain America and Captain Marvel team up to face a new cosmic threat that's headed towards Earth. They have to combine their unique skills, with Captain America's strategic mind and combat experience on the ground, and Captain Marvel's incredible cosmic powers in space battles.
Well, you could write a 'Captain America experiment fanfic' where the experiment was part of a larger, inter - dimensional experiment. Maybe in this fanfic, Captain America's experiment not only changed him physically but also opened a portal to another dimension. And from that dimension, new threats or allies come into play. You could also have a story where the experiment was a test by an ancient civilization that was long forgotten, and as Captain America discovers the truth about the experiment, he has to deal with the implications of this ancient knowledge.
It would be amazing. Naruto's energetic and determined personality would contrast with the more serious nature of some DC characters and Captain America. His ninja skills could be used in unique ways in the DC or Marvel - like settings. For example, his shadow clone jutsu could be used to confuse enemies like the Joker or Hydra agents. Captain America's sense of justice would also fit well with Naruto's idea of protecting his village and friends.
Well, in some fanfics, they might make Captain America seem like a jerk to create an interesting plot twist. Maybe they show him being overly self - righteous or making bad decisions that go against his usual heroic image.
One idea could be a story where they discover the pregnancy during a time of peace after a major battle. They are both overjoyed but also a bit worried about how to balance their superhero duties with starting a family. Steve (Captain America) might be extra protective of Peggy, and they start making plans for a nursery in their home.