One possible plotline could be that the news spreads slowly across the universe. Different characters react in various ways. Some are in awe of Gohan's power, while others might be jealous. For example, Vegeta could be initially angry that Gohan achieved such a feat instead of him, but then gradually come to respect Gohan more.
Some social media groups dedicated to Dragon Ball might also be a good place to look. For example, on Facebook groups or Reddit subreddits about Dragon Ball. Fans in these communities are usually quite passionate and helpful. They might be aware of such a fanfiction or could even write one if it doesn't exist yet.
Trunks could also be a popular character in such fanfictions. He might be curious about Gohan's interactions with Cell and get involved in their affairs. His time - traveling knowledge could add an interesting twist to the story. Also, Vegeta could be included. His pride might not allow him to accept Gohan getting too close to Cell and he could try to put an end to their relationship or partnership in the fanfiction.
One idea could be to focus on Gohan's internal struggle during the Cell Games. Maybe he's doubting his abilities even more than shown in the original, and it's through his friends' and family's words of encouragement that he finally finds his resolve.
Well, this fanfic could be quite interesting from a character - development perspective. If Cell kills Gohan, it could change the entire dynamic of the Dragon Ball world. For example, Vegeta might be forced to step up in a different way, or the Z - fighters might have to completely reevaluate their strategies. It might also show a different side of Cell, perhaps a more menacing and victorious side that we haven't fully seen in the original series.
In the manga, Gohan never managed to defeat Goku. Their battles often ended with Goku coming out on top or the fight being interrupted for some reason.
In fanfiction, Gohan could have a secret power that he discovers during the Cell Games. This power could be related to his Saiyan heritage in a new and unexpected way, like being able to tap into an ancient Saiyan ability that no one else knew about. It could completely change the course of the fight against Cell.
In this fanfiction, Gohan and Videl might have an interaction where Videl tries to understand Gohan's Saiyan heritage. Gohan could explain it to her, and this could create a deeper connection between them. They could also have a moment where they work together to find a weakness in Cell. Videl's human perspective might give Gohan an idea that he hadn't thought of before.
In a fanfiction centered around Gohan's field trip to the Cell Games, there are so many possibilities. The other Z - fighters could be involved in different ways. For example, Goku might give Gohan some tips on how to handle the situation without revealing too much to his classmates. Vegeta could be there, grumbling about having to deal with a bunch of kids around during a potential battle. And Gohan himself would be in a tough spot, trying to enjoy the field trip as a kid but also being aware of the danger that could erupt at any moment. He might even use this as an opportunity to teach his classmates some valuable lessons about courage and self - sacrifice.
One common theme is redemption. Writers often explore the idea of Cell being redeemed in some way through his relationship with Gohan. Another theme is the power of friendship or an unlikely alliance. Since they were enemies originally, seeing them come together in fanfiction is quite interesting.