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.
Well, perhaps Captain America could be on a mission to seek an ancient Asgardian weapon to help in the fight against a new threat on Earth. He might meet Thor and the other Asgardians, and have to prove himself worthy in their eyes, just like he did in his own world.
The Night King could be a great antagonist. His army of the dead and his own powerful magic would pose a huge threat to Captain America. Cap's used to fighting human foes, but the Night King is something entirely different.
He could meet Peggy Carter. Since he had a strong connection with her in the past, it would be a very emotional reunion. They might share some unspoken feelings that were left unexpressed before.
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.
She could meet a very smart science teacher who is intrigued by her powers and wants to study them scientifically.
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.
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.
In this fanfiction, he could also meet his past self. It would be an interesting encounter. They might have a conversation about his future experiences and how to better protect the world. And he may use his knowledge of the future to train his past self, making him an even better hero.
There's also 'Captain America: Reborn'. In this fanfic, Steve Rogers has to face a new threat that is specifically targeting his ideals. It's a great read as it explores his unwavering beliefs and how he inspires those around him even in the face of seemingly insurmountable odds. It also has some unique interpretations of his powers and abilities.