Who could be the main antagonist for Captain America in a 'Captain America in Westeros' fanfic?

Maybe it's an old enemy who has somehow survived and is now more powerful. They could be seeking revenge on Captain America for past defeats. For example, Red Skull could have found a new way to return and cause trouble.

The main antagonist could be a powerful sorcerer. As I mentioned before, in the context of a magical curse causing the weight gain. This sorcerer could have his own motives, like trying to take over the world by first weakening the Avengers' most iconic figure. He could use his dark magic to mess with Captain America's body and make him gain weight, and then use this as a distraction while he executes the rest of his evil plan.

He could also meet Odin. Odin might view Captain America as an interesting mortal from Midgard and might have some words of wisdom or a task for him to complete during his stay in Asgard.

It could be a rogue Amazon who disagrees with the idea of an outsider like Captain America being on Themyscira. She might see him as a threat to their way of life and try to drive him out, or even worse, harm him.

Well, in this fanfic, Captain America would stand out immediately. His costume and shield would be quite the spectacle in Westeros. He might find himself in the middle of the power struggles between the Lannisters and the other houses. His leadership skills could be put to the test as he tries to unite the different factions against a common enemy, like the White Walkers, or just to bring peace to the Seven Kingdoms.

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.

Well, it's hard to say who the 'best' is as it depends on personal taste. But some popular authors in the fanfic community often include those who have a deep understanding of the characters. For example, 'MarvelFan45' has written some really engaging stories that explore the relationship between Captain Marvel and Captain America in different scenarios. Their writing style is very descriptive, making you feel like you're right there with the characters.

There's also the story of Steve's first real mission as Captain America. He was sent on a USO tour at first, but when he got the chance to fight in the real battle, he showed his true courage. He didn't care about the danger and just wanted to do his part to save his comrades and fight against the bad guys.

Often, there will be some of Captain America's old friends or comrades in these fanfics. For example, Bucky Barnes might make an appearance. He could be like an uncle figure to the son, teaching him about the old days and some combat skills. There could also be new characters created specifically for the fanfic, like a young sidekick for the son who has different powers and a different background, adding more depth and variety to the story.

Captain America could fit in by sharing his sense of morality and leadership. In the TOS universe, which often deals with complex moral and ethical dilemmas, his straightforward and noble values could provide a different perspective. He might be involved in diplomatic missions, using his charisma and integrity to negotiate with alien races. Also, his military experience could be applied to strategic planning during the crew's missions.