Another theme might be growth. As they interact, they could both grow as characters, learning from each other's strengths and weaknesses. For example, Butters' naivete might be balanced by Scott's more cautious nature. And there could be a theme of acceptance, where they accept each other for who they are despite their differences.
I'm not sure specifically which ones are the best. You could try searching on popular fanfiction websites like Archive of Our Own. There might be some interesting stories there about Scott Malkinson and Butters Stotch.
One common theme could be friendship. Given their characters in the show, exploring how they become closer friends or support each other through different situations. For example, dealing with school bullies together.
One common theme is friendship. Despite their differences, their friendship is often explored in various ways, like how they support or challenge each other.
Another theme is the exploration of their personalities. Writers like to dig deeper into what makes Butters so naïve yet kind - hearted and Cartman so brash and manipulative, and how these traits interact when they are in a relationship, whether it be a friendship or something more complex.
One common theme is friendship turned into something more. Since they are both characters from South Park, their initial acquaintance as friends can develop into a deeper relationship in the fanfiction.
One common theme is the exploration of forbidden love. Since they are both male characters in the South Park universe, their relationship might be seen as unconventional by some in the fictional setting. Another theme could be the power dynamics, like Kenny being more street - smart and Butters being a bit more sheltered, so there can be a play on who has more influence in the relationship.
Another common theme is growth. Their relationship can be a catalyst for their individual growth. For example, Butters might become more confident through his interactions with Kenny, and Kenny might become more empathetic towards Butters. This is often shown in fanfics through different story arcs.
In South Park Kyle x Butters fanfiction, a frequent theme is the contrast between their personalities. Kyle's more assertive nature and Butters' gentle side create interesting interactions. Also, the theme of acceptance is common. They accept each other's flaws and quirks, which is a nice aspect to explore in the fanfics.
A frequent theme in vampire Butters fanfiction is the idea of power and control. Since Butters is now a vampire, he has new powers, but he also has to learn how to control them. This can lead to some really interesting plotlines. Also, the theme of acceptance is often seen. Whether it's Butters accepting himself as a vampire or his friends accepting him in his new state. There are also some fanfictions that explore the theme of good vs evil within Butters, as vampires are often seen as evil in popular culture, but Butters is a character with a good heart.
One common theme is friendship. Fanfictions often explore Butters Snaps' relationships with other characters and how those friendships develop or face challenges.