It could be that they enjoy the diverse perspectives in fanfiction. Different writers bring their own ideas and emotions to the stories, so there's always something new and interesting to read. Jimmy and Cindy might be really into exploring these various viewpoints.
Once upon a time, Jimmy and Cindy met at a small coffee shop. Jimmy was immediately smitten by Cindy's bright smile. He mustered up the courage to say hello, and from that moment on, they started to share their interests, dreams, and fears. Their love grew slowly but surely, like a beautiful flower blooming. They went on walks in the park, held hands under the moonlight, and created memories that would last a lifetime.
Once upon a time, in Retroville, Jimmy Neutron, the boy genius, noticed something strange about Cindy. One day, he saw her with a pale complexion and a strange glint in her eyes. It turned out Cindy had been turned into a vampire. Jimmy was determined to find a cure. He used his scientific skills to create various potions. After many trials, he finally found the right one and Cindy was back to normal.
One common theme is friendship. Since they are characters who interact a lot, many fanfictions explore their evolving friendship over time. For example, stories about how they support each other during difficult times at school.
Maybe Jimmy and Cindy are both in witness protection programs but don't know about each other at first. They meet in a small town where they are both hiding. As they start to get to know each other, they fall in love. But then they discover each other's true identities and the danger that comes with it. Their love is put to the test as they have to decide whether to stay together and face the threats or part ways to keep each other safe.
Love, in a more platonic or budding romantic sense, can be a theme as well. Some fanfictions explore the idea of Jimmy and Cindy having feelings for each other that they are not quite sure how to handle. This adds an interesting dynamic to their relationship and the overall story.
Another theme is the continuation of their adventures. In many fanfictions, just because they are married doesn't mean they stop being curious and having exciting escapades. Their married status might even add a new dimension to their adventures, like having to consider each other's safety more deeply.
One common theme could be the journey of their relationship. It might explore how they first met, the initial attraction, and how their love developed over time.
Romance is also quite prevalent. Many fanfictions focus on the two characters falling in love, with all the typical romantic tropes like first kisses and confessions of love. They might write about how their relationship overcomes obstacles in their world.