Love triangles are a popular theme as well. Not just with Elena, but sometimes new characters are introduced and they both get involved in a love triangle situation. Also, the theme of self - discovery is there. They both learn more about themselves through their relationship with each other. For instance, Damon might discover a more caring side of himself through his interactions with Stefan.
The theme of rivalry also pops up a lot. They are often in competition for things like Elena's love or power in the vampire world. But at the same time, there's the theme of unity. In the face of greater threats, they come together and their bond is strengthened. For example, in some fanfics, when a new, more powerful vampire arrives in Mystic Falls, they put aside their differences to fight it.
One common theme is loyalty. Their status as mates often means they have to be loyal to each other no matter what challenges they face, like in many fanfics where other vampires try to break their bond. Another theme is sacrifice. They might sacrifice their own desires or safety for the sake of their mate.
One common theme is love triangles. Since it involves Damon, Stefan and an OC, often there's a complex love situation. For example, the OC might be attracted to both brothers in different ways.
Love is an overarching theme. It can be brotherly love or a more complex love. Damon's care for Stefan shows that he loves him deeply. And growth is also a theme. Through Damon taking care of Stefan, both of them may grow as characters, learning more about themselves and each other.
One common theme is the exploration of a deeper emotional bond. Since they are brothers in the original show, fanfiction often delves into what if there was more to their relationship. Another theme is the struggle with their vampire nature in the context of a new relationship. For example, how their bloodlust might affect their feelings for each other.
One common theme is the struggle for acceptance. Since Bella is the mate of both Damon and Stefan, there's often a plotline about how the vampire community or their friends accept this unusual relationship. For example, they might face judgment from other vampires who don't understand this triad.
One common theme is love triangle. Since Bonnie, Damon and Stefan are all connected in the Vampire Diaries universe, the love triangle between them is often explored. It creates a lot of drama and tension.
Love and sacrifice are also common themes. Stefan and Damon both love Elena deeply and are willing to make sacrifices for her. This could range from giving up their own power to save her life. And there's also the theme of redemption. Damon, who has a darker past, might be on a path of redemption because of Elena's influence. He tries to be a better person, which creates an interesting dynamic in the fanfics.
One popular theme is redemption. Many fanfictions explore Damon's journey towards redemption, with Stefan often playing a crucial role in it. For example, there are stories where Damon tries to make up for his past wrongs because of Stefan's influence.
Family loyalty is a big one. These stories often explore how far the brothers will go to protect each other. For example, in many fanfictions, Damon and Stefan will put their lives on the line for their younger brothers.
A theme that frequently shows up is redemption. Klaus, being a complex and often villainous character, may be on a path to redemption in some fanfictions, with Stefan either helping or hindering. Also, power dynamics play a role. Klaus is very powerful, and Stefan has his own set of abilities, so how they interact in terms of power is a common theme. For example, in some stories, Stefan has to find ways to level the playing field when dealing with Klaus.