In some of the stories, Baron Zemo's redemption arcs are fascinating. He was a character who had done a great deal of wrong, but there were moments where he was faced with choices that could lead him towards a more positive path. His internal struggle between his villainous nature and the possibility of change made for very thought - provoking stories. For example, when he was forced to team up with heroes in a situation where their common enemy was even more dangerous. This put him in a position where he had to reevaluate his values and actions.
One character that would be interesting to include is Isaiah Bradley. His story is so rich and tragic, and his connection to the super - soldier program could bring a whole new layer of depth to the fanfic. Additionally, Agent 13 could be included. She could be involved in some sort of political intrigue that Falcon and Winter Soldier have to navigate through. And Redwing! Sam's trusty drone could have its own sub - plot, like getting hacked and Sam having to rescue it.
In the original story, it focuses on the relationship between Falcon and Winter Soldier. Falcon is a hero in his own right, with his flight abilities and combat skills. Winter Soldier, Bucky Barnes, has his own complex past as a brainwashed assassin. The story often involves them dealing with threats both from their pasts and new emerging enemies while trying to find their place in a post - Captain America world.
One common theme is redemption. Many fanfictions try to show Zemo in a new light, perhaps on a path to redeem himself with the help of the oc. For example, the oc might be the catalyst for Zemo to question his actions and strive for a better self.