Friendship is a very common theme. Bucky and Sam often start off with some differences but gradually become good friends. Another is redemption. Bucky, with his past, often has a journey of redemption in these fics, and Sam helps him along the way.
Teamwork is also big. They are both superheroes, and many fanfics explore how they work together to face threats. For example, in some fics they fight against new villains that require their combined skills. It's about how they learn to rely on each other's strengths.
One common theme is friendship. Since they come from different backgrounds in the Marvel universe, their journey of forming a friendship is often explored. For example, Bucky has his past as the Winter Soldier, Sam is a military man, and Peter is a young superhero. Their differences and how they overcome them to become friends is a big part of many fanfics.
A common theme is friendship. They've been through a lot in the Marvel universe, and fanfictions often explore how they become true friends. For example, stories might show Bucky opening up to Sam about his past as the Winter Soldier, and Sam being there for him.
One common theme is redemption. Bucky often has a troubled past in these fanfics, and the story revolves around him finding a way to make amends or move forward. Another theme is friendship. He forms new relationships that help him grow. Also, love is a common theme, whether it's romantic love or the love of friends and family.
One common theme is self - discovery. Bucky, often coming from a complex past, uses his time in Paris to find out more about who he is without the pressures of his usual environment.
One common theme is redemption. Bucky has a dark past, and in Wakanda, he often finds a path towards redemption. The peaceful and advanced nature of Wakanda provides a backdrop for his transformation.
One common theme is redemption. Bucky has a complex past and Tony often has to come to terms with that. Another theme is friendship. They are two very different characters but in fanfic they often find common ground and become friends.
One common theme is redemption. Both Bucky and Natasha have dark pasts, and many fanfics explore how they find redemption through their relationship with each other. For example, they help each other come to terms with the things they've done.
Trauma and recovery are very common themes. Given his history of being experimented on and used as a weapon, fanfics often deal with how he copes with his past traumas. Love is also a theme. Sometimes it's romantic love, where Bucky finds someone who can accept him for who he is, with all his flaws.
Protection is also a big theme. Bucky, with his enhanced abilities, feels the need to protect his nephew from all kinds of threats. And sometimes, the theme of acceptance is there. The nephew has to accept Bucky's complex past and Bucky has to accept the new role of an uncle.
Another common theme is loyalty. They are extremely loyal to each other. In some fanfics, they'll go to great lengths to protect one another, even if it means going against the whole world. It's a very powerful aspect of their relationship that writers often explore.