Through shared battles. When they fight side by side against common enemies, they start to trust each other more. For example, in a fight against a group of powerful androids created by a mad scientist, they rely on each other's strengths. Goku uses his martial arts skills and Android 21 uses her technical abilities to analyze the opponents' weaknesses.
A good way is to introduce a conflict that only they can solve together. Maybe there is a powerful energy source that is causing chaos in the universe. Goku's physical strength and Android 21's knowledge of technology are both needed to stop it. As they work towards the solution, they gradually develop a closer relationship. This could involve them having to sacrifice something of their own for the greater good, which in turn strengthens their connection.
By exploring their differences. Goku is a Saiyan with a love for fighting and food, while Android 21 has a more complex backstory and a different view of power. In the fanfiction, they can have conversations about these differences. Android 21 might be intrigued by Goku's simple yet pure approach to life and fighting, which could lead to a deeper bond.
In the fanfiction, their relationship could be one of mutual admiration. Kid Goku would look up to Future Goku for his experience and power. Future Goku, on the other hand, would be charmed by Kid Goku's innocence and raw potential. They could train together, and during this process, they would form a strong brother - like relationship.
The relationship could start with hostility. Towa might see Goku as a threat to her plans and Goku sees her as an evil force. But then, when they are forced into a situation where they need to rely on each other, like being stranded in a strange realm. They begin to see each other's strengths. For example, Goku might admire Towa's intelligence in dealing with the strange environment, and Towa might be impressed by Goku's unwavering determination.
Well, at first they might be a bit wary of each other. But as time passed, they'd discover their common interests like the pursuit of strength. Goku's positive attitude would influence Android 18, and she would in turn help Goku with things like problem - solving from her android - smart perspective. As they grew older in the fanfiction, this relationship could become a very deep and important one, with them having each other's backs no matter what.
Perhaps the goddess has the ability to see different timelines. She sees a future where Goku is the most important figure in the universe's survival. So she travels back in time to meet him when he's still young. She becomes his mentor, guiding him not just in power but also in understanding the greater cosmos. As Goku grows up, he starts to see her not just as a mentor but as a love interest, and they develop a relationship that spans different stages of Goku's life.
It could start as a mutual respect for each other's power. Goku would admire Android 21's combat abilities, and Android 21 would be intrigued by Goku's Saiyan strength.
Their relationship could be developed realistically by having them work towards a common goal. For example, they might be trying to stop a new villain from taking over the world. As they plan and execute their strategies, they see the best and worst in each other. Gohan might see Android 18's determination even in the face of great danger, and Android 18 might see Gohan's selflessness. These experiences can bring them closer and form a relationship based on trust and admiration.
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.
Their relationship could develop into a deep friendship. Goku, being the kind - hearted fighter he is, would likely accept Android 18 for who she is. And Android 18, seeing Goku's strength and good nature, would start to respect him more and more.
The interaction might start with suspicion. Goku, always on guard for threats to the Earth, would be cautious around Android 21 at first. But Android 21 could be intrigued by Goku's power and simplicity. As time goes on, they could start training together, which would be an interesting interaction as Goku's training methods are very different from what Android 21 is used to.
Goku and Launch could start with a simple encounter involving lemons, like Goku accidentally bumping into Launch while she is carrying a basket of lemons. This could lead to an apology and then an invitation to share some lemonade. From there, their relationship could grow as they find more common interests related to lemons, such as making lemon pies together.