Perhaps a rogue Saiyan from another part of the universe. This Saiyan has heard about the Super Saiyan powers on Earth and wants to prove his superiority. He shows up at the Cell Games and challenges Goku and Gohan. He has a different fighting style, more brutal and less honorable than the Saiyans on Earth. His presence adds a new layer of conflict as Goku and Gohan have to decide whether to fight him on his terms or uphold their own values.
One possible interesting plot could be Gohan unlocking a new, unexpected power level during the Cell Games. For example, instead of just going Super Saiyan 2, he could access a form that combines the power of both Goku and his own latent abilities. This new form could have unique characteristics like different colored ki blasts or enhanced speed and strength that not only surprises Cell but also gives Gohan a whole new perspective on his power.
It could be someone from Goku's past who has a vendetta against him and takes advantage of the chaos during the Cell Games. For instance, an old enemy who was thought to be defeated but managed to come back stronger and wants to finish Goku off while he's weakened from the fight with Cell.
Well, Goku is surely one of the main characters as it's related to the Cell Games. He is the central figure in the fight against Cell.
One possible fanfic could be about Goku's intense training before the Cell Games. He might be shown pushing his limits in the Hyperbolic Time Chamber, trying out new techniques and forms to defeat Cell. Maybe he discovers a new power level that no one, including himself, expected.
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, in this fanfiction, Gohan and Videl could have a really intense moment. Maybe Gohan shows off his amazing power during the Cell Games in a way that makes Videl fall for him even more. She might be in awe of his strength and determination.
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.
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.
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 interesting concept could be new power - ups for Goku. Maybe he discovers a unique form during the Cell Games in the fanfic.