Another adventure could be them traveling back in time. They could end up in a time period where the Z - Fighters are just starting out. Gohan would be in a strange situation, seeing his younger self and his friends. Android 18 would be equally out of place. But they'd have to find a way to fit in while also dealing with any threats that might emerge from their time - traveling. This could lead to some really interesting interactions with the younger versions of the characters, and they'd have to be careful not to disrupt the timeline too much.
They could have adventures where they explore new planets. Gohan's curiosity as a Saiyan and 18's fearless nature would make them great explorers. Maybe they'd discover a new form of energy on an uncharted planet that could help Gohan become even stronger or give 18 some new abilities.
In a fanfiction, Future Gohan and Android 18 could have a relationship based on redemption. Android 18 has done some not - so - great things in the past. Gohan, being the good - hearted Saiyan he is, could see the potential for good in her. He might try to guide her towards a more positive path. This could involve Gohan protecting 18 from other threats, and in return, 18 could use her android powers to help Gohan in his battles. Their relationship could be a slow - burn type, gradually evolving from distrust to a strong friendship or even more, depending on how the fanfiction unfolds.
Well, they could have an adventure in a new dimension. Naruto's ability to use chakra and Gohan's ki powers could be combined in unique ways. For example, they could use their combined energy to break through barriers that are otherwise impossible to cross. And they would surely make new friends and enemies in this new dimension.
A possible relationship is that of friends. They respect each other's strength and abilities. Android 18 might admire Gohan's determination and Gohan could be impressed by Android 18's combat skills.
In such a fanfiction, perhaps future Gohan could warn present - day Gohan about upcoming threats that he has faced in his own timeline. He might share his experiences and knowledge, which could make present Gohan a stronger fighter and a wiser person.
They could go on a quest to find a powerful dragon ball that has been lost. Goku's sense of adventure and 18's combat skills would be a great combination. Along the way, they would face various enemies. Goku would use his super - fast speed and powerful attacks, while 18 would use her android abilities like energy absorption to deal with the threats.
Perhaps they would start a family. Gohan's Saiyan genes and Android 18's unique android nature could result in some really interesting children. Or maybe they would have to deal with villains who target their relationship as a weakness.
Well, it could be about a very different future for Gohan. Maybe in this fanfiction, Gohan faces new and unique challenges that are not part of the original story. The 'lemon' aspect might imply some sort of romantic or spicy sub - plot. For example, it could be about Gohan's love life in a future where he has to balance his heroic duties with his personal relationships.
Their relationship could also develop through mutual respect. Gohan respects Android 18's power and her ability to make her own decisions. Android 18, on the other hand, respects Gohan's intelligence and his role as a protector. This mutual respect could be the foundation for a romantic relationship. For instance, they could start training together. During training, they would learn more about each other's limits and capabilities. This closeness during training could lead to a spark of love as they see each other in a different light, not just as allies but as potential lovers.
Maybe in the fanfic, Gohan is the first one to notice Android 18's different side. He begins to befriend her, and as they interact more, Android 18 falls in love. Their relationship then faces challenges from the Z - fighters who are initially suspicious of Android 18's motives.
They could embark on a journey to stop a powerful dark force that was unknown in Minato's time. Naruto, with his future knowledge, could lead the way and show Team Minato new ways to fight.