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.
Another theme is the supernatural. Given that they are from a world full of vampires and witches, they often deal with supernatural threats together. Like in many fanfics, they might fight against a powerful dark magic or a new breed of vampires.
Love is also a common theme, especially the unexpected kind. Since in the original story they may not be the most obvious couple, in fanfiction their relationship can develop in unique ways. Their love might be a slow - burn one, starting from mutual respect and gradually turning into something more passionate.
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.
Well, a big theme is 'unlikely friendship turned love'. They start as acquaintances or even enemies in some cases, and then their relationship evolves into love. 'Discovering new powers together' is also a theme. As Bonnie has her witch powers and Stefan his vampire abilities, sometimes in fanfictions they discover new ways to combine or enhance their powers when they are together. And 'protecting each other' is a theme that shows their loyalty and deepening bond.
One great Bonnie and Stefan fanfiction is 'A Different Kind of Bond'. It explores their relationship in a unique way, delving into how they might support each other through the various challenges in the vampire - witch world. Another is 'Bonnie and Stefan: The Unlikely Alliance' which shows them teaming up against common enemies and in the process, growing closer. There's also 'Stefan and Bonnie's Hidden Journey' that takes readers on a journey of discovery as they find new aspects of their connection.
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.
Often, there is a theme of secrecy and forbidden love. Since they are both characters in a somewhat dark and spooky game setting, their relationship might be seen as something that has to be hidden from others. This adds an element of tension and drama to the fanfiction, as they have to navigate their feelings while also dealing with the external threats and mysteries of the FNAF world.