Red Skull could be the villain. Since he has a long history with Captain America, in a fanfiction where Captain Carter is involved, he could be resurrected or have found a way to cross over from another dimension. He would see Captain Carter as an interesting new threat and Captain America as an old foe to be finally defeated.
Baron Zemo could also be the villain. He might be plotting to start a war between Captain Carter and Captain America. He manipulates events to make it seem like they are threats to each other. But as they start to figure out the truth, they join forces to take down Zemo who is hiding in the shadows, pulling the strings and trying to destroy the peace that both heroes have been fighting to protect.
One possible plot could be that they meet in an alternate universe where timelines have merged. Captain Carter and Captain America initially have a bit of a misunderstanding as they come from different versions of heroics. But then they realize they share the same values of justice and freedom. They team up to fight a common enemy that is threatening both their worlds, like a powerful time - traveling villain who wants to rewrite history to suit his evil plans.
Baron Zemo could be a great main villain. He could be plotting to create chaos between the two heroes. He might use his intelligence to set up situations where Captain America and Black Widow suspect each other, all while he is working on a larger scheme to take over a powerful weapon or organization.
I think Hermione would be really interesting too. She is so intelligent and knowledgeable about magic. When she meets Captain America, she would probably be very curious about his world and how things work without magic. She could be the one to try and find a way to bridge the gap between the two worlds, like trying to figure out how Muggle technology and magic could work together.
The Red Skull could be the main villain. He could team up with some other super - villains or get his hands on some kryptonite - like substance. He would try to use his knowledge of Captain America's past and Superman's weakness to defeat them. He wants to rule the world and sees these two heroes as the biggest obstacles in his way.
Captain America would probably remain calm at first. He's used to being in tough situations. He'd try to talk to Loki, reason with him, and find out what Loki wants.
No, Sharon Carter did not become Captain America in the comics.
Wolverine's gruff and sometimes anti - social nature might be at odds with Captain America's more patriotic and team - oriented personality. Wolverine might not care much for Captain America's flag - waving ideals at first. But as they spend time together, Wolverine could come to appreciate the values that Captain America stands for. And Captain America could understand Wolverine's more survival - based mindset. They could blend their personalities to form a more effective duo, with Wolverine's tenacity and Captain America's leadership guiding their actions.
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, they might start off as a bit cautious around each other. Captain America could be impressed by Superman's superpowers which are on a whole different level compared to his own enhanced human abilities. They could end up teaming up to fight a common enemy, like an alien invasion or a super - villain who is too powerful for either of them alone.
Friendship is a big theme. Despite their differences, the characters usually end up forming strong bonds. They learn from each other and support one another in facing various challenges. Another theme is the exploration of power. Captain America has his super - soldier abilities, and the Hetalia characters have their own skills and influence. How they combine their powers or deal with differences in power is often a part of the story.