In the main comic continuity, Captain America has typically been depicted as a white character. However, there have been alternate storylines and versions where the role has been taken on by characters of different races.
Sure. In the comic universe, Isaiah Bradley has taken on the role of a black Captain America. This addition brought more diversity and new storylines to the Captain America mythos.
Sam Wilson's journey to becoming Black Captain America is quite a tale. Sam was a veteran who had a strong sense of justice. When he became Captain America, he was in a difficult position. The public's perception was a big hurdle. But he was determined. He trained hard to be worthy of the shield. His backstory as a man who had seen the hardships of war and fought for what was right gave him the moral compass needed for the role. He had to deal with super - villains as well as the public's changing view of what Captain America could be. His story shows how anyone, regardless of race, can step up and be a hero, carrying on a great legacy in a new and exciting way.
Another possibility is a fanfiction set in an alternate universe. In this universe, Captain America and Black Widow are not part of the Avengers. Instead, they are partners in a detective agency. They solve crimes that are related to super - powered individuals, using their own unique abilities and intelligence.
In the comics, Captain America and Black Widow are not typically depicted as a couple. They have a professional relationship based on their roles as superheroes within the Marvel universe.
In the fanfiction, their relationship could be complex. They've been through so much together as comrades in the Avengers. As parents, they might have different parenting styles. Captain America could be more open and idealistic, while Black Widow is more cautious and practical. But they both love their child deeply and work together to keep the child safe from the threats that come from their superhero lives. For example, when the child wants to join a mission too early, they have to work out how to handle it as a couple.