My answer was wrong. In the Captain America movies, only Captain America: The Avengers had a character like Ying Xingyi. I mixed up the names of the other characters and caused unnecessary confusion. Thank you for pointing out my mistake.
In 'Captain America 2', Steve Rogers is still adjusting to the modern world. He discovers a conspiracy within S.H.I.E.L.D. Hydra has infiltrated it. There are intense action scenes as he teams up with Natasha Romanoff to fight against the bad guys. They try to expose the truth and stop Hydra's evil plans. In the end, S.H.I.E.L.D. as they knew it falls, but they manage to save a lot of lives and start a new chapter in the fight against evil.
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.
The story of 'Captain America: Winter Soldier' is complex. It mainly revolves around Steve Rogers adjusting to the modern world. Hydra has secretly infiltrated S.H.I.E.L.D. The Winter Soldier, Bucky Barnes, who was Steve's old friend, has been brainwashed by Hydra to be a deadly assassin. Steve discovers the truth about S.H.I.E.L.D. and Hydra's plot. He teams up with Natasha Romanoff to fight against this conspiracy and also tries to save his friend Bucky from the control of Hydra.
In the full story, first Steve discovers the conspiracy. Then he and Natasha start to investigate. They have many encounters with Hydra agents. And the fall of S.H.I.E.L.D. as they expose Hydra is a major event.
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.