Maybe in a post - battle scenario, Goku and Android 18 are left alone to recover. They begin to have conversations about their different origins. Goku shares about his Saiyan heritage and training, while Android 18 talks about her creation by Dr. Gero. This exchange could lead to a deeper emotional connection between them.
A possible plot could be that Android 18 gets injured during a fight and Goku takes it upon himself to protect and heal her. This close proximity leads to the development of feelings, which is where the 'lemon' part might come in. Their relationship could be a secret at first as they are from different 'worlds' in a sense, with Goku being a Saiyan hero and Android 18 being an android once created for destruction.
It might also be a story about self - discovery. Android 18 could be exploring her more human side with Goku's influence. Goku, on the other hand, could learn more about the androids and how they are not all just mindless killing machines. The 'lemon' aspect might imply some sort of budding relationship that is full of passion and challenges as they come from very different backgrounds.
Another storyline could be a time - travel one. Android 21 somehow gets sent back in time and meets a younger Goku. This would be really interesting as she would have knowledge of future events and technologies. Goku, being his curious self, would be intrigued by her and want to learn from her. They could team up to prevent some of the future disasters that Android 21 knows about.
Another storyline could be that Bulma creates a new device that has some unexpected side effects. Goku is the only one who can help her fix it, and during this process, they accidentally get sent to a parallel universe. There, they have to work together to find a way back home, all while their relationship blossoms in this strange new world.
Another possible storyline is that Android 21, who is usually seen as a bit of an outcast, finds acceptance in Goku's group. Goku encourages the others to give her a chance. They then go on adventures together, with Android 21 constantly evolving not just in power but also in her understanding of the world around her.
In some fanfics, other characters might also play a role. For example, Krillin, who was once in a relationship with Android 18. His presence could add an interesting dynamic, like jealousy or a sense of competition, to the relationship between Goku and Android 18.
One possible storyline could be that Goku is accidentally transported to Alucard's world. They start off as enemies but then gradually learn about each other's powers and come to respect one another. Another could be that a powerful villain manipulates them into fighting each other. In this case, they might realize they are being used and team up against the real enemy.
One interesting storyline could be Goku and Android 18 teaming up to fight a new, powerful enemy that neither of them can defeat alone. They have to learn to combine their skills and powers in unique ways.
In 'Goku betrayed fanfiction', a common plot might be the corruption of his power. Let's say Goku discovers a new form of power that is seen as too dangerous by others. His friends and even some of the Z - fighters fear that he'll lose control and turn on them. So they decide to betray him first to protect the Earth. Another aspect could be a political betrayal. If there were some sort of intergalactic politics involved, Goku might be sacrificed or betrayed by his own side to make a deal with a more powerful alien race. And then there's the idea of a time - travel - related betrayal. Maybe someone from the future comes back and convinces everyone that Goku will cause a great disaster in the future, causing them to betray him in the present.
Well, it could be a relationship based on power dynamics. Goku is extremely powerful, and Android 21 is no slouch either. They might engage in battles that gradually turn into a form of respect for each other's abilities. And then, this respect could evolve into a deeper connection. For example, Goku could teach Android 21 about the joys of a fair fight, and she could in turn show Goku some of her unique Android - related skills or knowledge.