One good one to start with could be 'The Unlikely Bond'. It really delves into the unique friendship between Kyle and Kenny and how it could potentially develop into something more. It has great character development and a really engaging plot that keeps you hooked from the start.
One common theme could be friendship evolving into something more. Since Kyle and Heidi might start off as friends in the original context, fanfics often explore how that relationship deepens romantically.
I would recommend 'Kyle in the City'. In this fanfiction, Kyle and the reader go on an adventure in a nearby big city, which is a change from the usual South Park setting. It's full of exciting moments and character development. 'Mystery with Kyle' is another interesting one, where they solve a mystery together in South Park. It has an element of suspense and also shows how their relationship grows stronger during the process. And 'Kyle's Prom Night' which is about their experiences at the South Park prom, a really sweet and romantic story.
Friendship is a very common theme. Since Kyle and Stan are friends in the original show, many fanfics explore how their friendship can grow and change. They might face challenges together and come out stronger.
Growth is also a theme. Fanfics might show how Kenny and Kyle grow as individuals while also growing in their relationship with each other. They could learn new things about themselves and each other as the story progresses.
Another common theme is personal growth. The fanfics might show how Eric and Kyle learn from each other and become better versions of themselves. They could influence each other's attitudes towards things like school, family, or their own self - esteem.
A frequent theme in Cartman x Kyle fanfiction is the idea of redemption. Cartman, being the more controversial character, often has a journey of self - improvement in relation to Kyle. It could be that he realizes the error of his ways in how he's treated Kyle. Also, the theme of acceptance is common. They learn to accept each other's flaws and differences. In some stories, they might even come to accept a romantic or at least a very close emotional connection between them.
One common theme could be friendship evolving into something more. Since they might start as friends in the original context, fanfic writers often explore the idea of their relationship deepening romantically.
One common theme is friendship. Despite their differences in the show, in fanfics, they might explore a deeper, more complex friendship. Another theme could be rivalry, but in a different context, like a friendly competition that turns into something more.