One common theme is friendship. Gene and Louise might be shown as having a deepening friendship through various adventures. Another theme could be family - like relationships, where they support each other like siblings.
I think Archive of Our Own (AO3) is also a great place to find 'gene x louise fanfiction'. It has a large collection and a good tagging system. You can filter the stories based on your preferences like the rating, word count, and specific themes. There could be some really creative takes on the relationship between Gene and Louise in those fanfictions.
One great 'Gene x Aphmau fanfiction' is 'The Unexpected Bond'. It delves into how Gene and Aphmau, two very different characters, form an unlikely friendship that gradually turns into something more. The story has really good character development and the author does a wonderful job of staying true to their personalities.
A common theme is the 'opposites attract' idea. Since Louise is bold and Rudy is shy, their differences make for an interesting dynamic in many fanfictions.
One possibility is that it could be an ancient genetic trait passed down from a long - forgotten clan in the Naruto universe. Maybe this clan had some unique powers that were lost over time, and the X gene is a remnant of those powers.
I'm not entirely sure specifically about 'gene x jailbreak fanfiction' as it could be a very niche or even a made - up concept in a particular fan community. It might involve a story where the concepts of 'gene' (which could refer to genetics, a character named Gene, or something else related to the term) and 'jailbreak' (which often means breaking free from confinement, perhaps in a technological or a more metaphorical sense in the story) are combined in a fictional narrative.
Some fanfiction could focus on the relationship between Louise and Gene as they grow older. It could explore how their sibling bond changes over time. They might have different interests as they get older, but still come back to their shared love for the family burger business and the unique family dynamic they have.
There could be a fanfiction where Louise and Colbert are in a post - apocalyptic world. They team up to survive against all odds. They have to find food, shelter, and protect themselves from dangerous gangs. Along the way, they learn about each other's strengths and weaknesses and form a deep bond.