Well, a cool plot could be that Android 18 discovers Gohan has a hidden power that even he doesn't fully understand. She decides to train with him to help him unlock it. As they train, they face various challenges and their relationship grows. Or perhaps there's a story where an evil android is created that can control other androids, and Android 18 has to rely on Gohan to free her from its control. They then go on a journey to destroy this new threat.
One idea could be a story where Gohan and Android 18 team up to protect the Earth from a new, powerful threat. They start off as reluctant allies but gradually develop a deep respect for each other's abilities. Another plot could be a time - travel story where they go back in time and have to prevent an event that changes their future relationship. Maybe they end up having to work together to stop a younger version of Cell from evolving further.
Maybe in the fanfiction, Android 18 gets injured while protecting Gohan from a new powerful enemy. Gohan then takes care of her and in that time of vulnerability, they realize their feelings for each other. This could lead to them exploring a relationship while also trying to figure out how to defeat the enemy that still lurks.
One idea could be Android 21's struggle to fit into a world that fears her. She has to prove that she's not a threat and tries to make friends. Another could be her discovery of new powers and how she uses them for good. Maybe she teams up with other characters to fight a common enemy.
One interesting story could be about Gohan and Android 18 teaming up to fight a new powerful enemy. They combine their unique skills, Gohan's martial arts and Android 18's android strength, to overcome the foe.
Well, a common plot might be that Gohan discovers a new side of Android 18. Maybe she has a hidden talent for cooking or art, and Gohan is really intrigued by this. They could start spending more time together exploring her newfound interests. Or perhaps there's a plot where an old enemy returns, and Gohan and Android 18 are the only ones who can stop it. In the process, they realize their feelings for each other are stronger than they thought. Another one could be a story where Android 18 is having trouble adjusting to life among the Z - fighters, and Gohan helps her fit in, which leads to a romantic relationship.
One idea could be a story where Gohan takes Chichi on a surprise adventure to a new planet he discovered during his Saiyan studies. They could encounter new forms of life and have to work together to overcome challenges.
A great plot idea would be Android 21 crossing into a world where technology is feared. She'd have to prove that not all advanced technology is bad. Also, she could cross into a world of pirates, using her skills to navigate the high seas and fight off other pirates.
One plot idea could be that Ash and Android 21 team up to fight a common enemy in a tournament. Another could be a story where Android 21 tries to understand human emotions through Ash's experiences. Or perhaps a plot where they travel through different dimensions together.
A possible plot is that Android 21, who has some glitches in her system related to her emotions, is healed by Gohan's kindness. As a result, she starts to develop feelings for him. They then have to deal with the fact that their relationship is not accepted by some in the Z - Fighter community because of Android 21's origin. This leads to a story full of drama and self - discovery for both of them.
One possible storyline could be them teaming up for a tournament. Gohan's martial arts skills combined with 18's strength would make for an interesting duo in the fighting arena. They could face various opponents and learn to trust each other's abilities more.
Another plot could involve Gohan being mistaken for a new metahuman in the DC universe. As he tries to find his way back home, he gets caught up in a conflict between the Justice League and a group of supervillains. His Saiyan powers could be the key to resolving the situation.