One possible plot could be that Black Widow is on a dangerous solo mission deep in enemy territory. Captain America, learning of her peril, rushes to her aid. He uses his shield to deflect incoming attacks and his combat skills to fight off the enemies one by one until he reaches her. Then they fight their way out together, with Captain America providing cover for the injured Black Widow.
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.
Well, at first it could be a simple comrades - in - arms situation. Captain America is just doing his duty to save a fellow Avenger. But as they escape from danger together, they start to have more respect for each other's skills. Black Widow might be a bit guarded at first, but seeing Captain America's selfless act makes her open up more.
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 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.
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 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.
Sure. There is a sort of love story in it. Steve's character is still haunted by his past love, Peggy Carter, which also plays into the emotional side of the story. Meanwhile, his relationship with Natasha is growing, and there are moments of tenderness and caring between them that hint at a possible romantic undertone.
Sure. In the comics, after Steve Rogers was believed to be lost or incapacitated, characters like Bucky Barnes and Sam Wilson have taken up the mantle of Captain America at different points.