The theme of sacrifice is also quite common. Steve sacrificed his life (or so he thought) by crashing the plane. Peggy sacrificed her personal life to a great extent for the SSR and the fight against Hydra. Fanfics will often put them in new situations where they have to make more sacrifices. And then there's the theme of time. The fact that Steve was frozen for decades while Peggy aged is a rich area for exploration in fanfics. They deal with how time has changed them and yet how some things between them remain the same.
Sure. 'The Long Road Home' is a great one. It delves deep into the relationship between Captain America and Agent Carter after Steve's return from the ice. It shows how they navigate their changed world and rekindle their connection. Another good one is 'Shield and Star'. It focuses on their early days in the SSR and how they worked together to take on Hydra threats.
Another theme is sacrifice. They often have to make sacrifices for the greater good or for each other. For example, one might give up a personal opportunity to help the other in a dangerous situation. And also, the theme of discovery. They are constantly discovering new things about each other and about the world around them in these stories.
Growth is a common theme. Since it's about a 'baby' Captain America, it often shows his journey of growing into the hero we know. Another theme is friendship, like his early bonds with Bucky. These fics might explore how those relationships were formed when he was younger.
Friendship is a very common theme. Since they are both part of the Avengers, many fanfics explore how they become friends and support each other. For example, they might show Hawkeye cheering up Captain America after a tough battle.
One common theme is identity. Since she's Captain America's daughter, she often has to figure out who she is apart from her father's famous name. Another theme is legacy. She has to decide whether to carry on her father's work or forge her own path. Family is also important, like how she deals with the loss of her father or the relationship with her mother if she's in the story.
The theme of friendship and teamwork also comes up a lot. Since Captain America is often part of a team, OCs in fanfics are usually involved in relationships with other characters. They learn to work together, trust each other, and support one another. This can lead to some great character - driven stories where the OC's relationships with characters like Bucky Barnes or Sam Wilson are explored in depth.
One common theme could be loss. Captain America has lost so much, from his old life in the 40s to friends over the years. So, a fic might show him crying over the loss of a comrade or the world he once knew.
One common theme is the contrast between their ideologies. Batman is more of a lone vigilante with a darker view of justice, while Captain America is a symbol of patriotism and upholds a more idealistic view. Fanfics often explore how they bridge this gap.
Another theme is the sister's own journey of self - discovery. Since she's related to a famous hero, she has to find her own place in the world. This could involve her developing her own powers or skills, like learning martial arts to be able to protect herself and help her brother. It's about her growing as a person while being part of Captain America's story.
Characterization. A good fanfic should accurately portray Captain America's noble and selfless nature, and Agent 13's intelligence and resourcefulness. If the writer can make the readers truly feel like they are the characters, it's a great start. For example, showing Captain America's internal conflict when faced with modern - day moral dilemmas while still staying true to his core values.