One common theme is self - discovery. Stefan often has to figure out his own sexuality and come to terms with it. For example, in many fics, he might start off confused but gradually realize his feelings for other male characters.
Love against all odds is also a big theme. Since in some fictional settings, homosexuality might not be fully accepted, Stefan has to fight for his love. It creates a lot of drama and emotional depth in the stories.
Another theme is 'redemption'. Stefan has his own dark past, and Bonnie is often portrayed as a powerful and good - hearted character. Fanfics may explore how Stefan can find redemption through his relationship with Bonnie, or how Bonnie helps him overcome his inner demons.
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.
One common theme is the clash of different worlds. Harry comes from a world of magic and wizards, while Stefan is from a world of vampires. So, there's often exploration of how these two very different worlds collide and interact.
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 clash of different vampire cultures. Since Stefan has his own vampire lore and the Twilight series has its own, seeing how they interact is often explored.
One common theme is redemption. Many fanfictions explore the idea of Katherine seeking redemption and how Stefan might be a part of that journey. Another is the theme of love and obsession. Their relationship was so complex in the show, and fanfictions often play with this idea, showing how their love or obsession for each other can change over time.
Love and sacrifice are common themes. Often, one of them has to sacrifice something for the other, like Stefan might sacrifice his safety to protect Caroline. It shows the depth of their love.
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.
One common theme is the idea of eternal love. Since they are in a supernatural world, their love is often depicted as something that can transcend time and death. For example, in many fanfictions, even if one of them is in danger or seemingly lost, their love remains unwavering.
One common theme is friendship. Stefan and Bonnie often start as friends in the fanfictions. For example, they might be friends first and then face challenges that make their bond stronger.