Then, introduce some shared experiences. Maybe they get trapped in a strange dimension together. In this new and dangerous place, they have to rely on each other's strengths. Goku's physical power and Frieza's cunning could be the keys to their survival. As they go through these experiences, they start to see each other in a new light and their relationship begins to change.
Well, friendship is also a theme. Despite their differences, they might form an unlikely friendship. In some fanfictions, they learn from each other. Goku might learn about strategy from Fem Frieza, while Fem Frieza could learn about determination and the will to protect from Goku. And of course, adventure is a big theme. They could go on quests together, exploring new planets and facing new challenges.
One common theme is redemption. Frieza is often portrayed as having a chance at redemption through his interactions with Goku. For example, in some fanfics, Goku's unwavering belief in the good in people (or in Frieza's case, beings) starts to make Frieza question his own evil ways.
In some lemon fanfiction, their interaction can be filled with tension. Goku, being the good - natured Saiyan, may be initially wary of Frieza. But as the story progresses, they might find common ground. For example, they could start to respect each other's power.
A plotline could start with Frieza hearing about Broly's power and being jealous. He then devises a plan to ambush Broly. But Broly, being extremely perceptive in his own way, senses Frieza's approach and is ready for the fight. As the fight progresses, Frieza realizes that Broly is much stronger than he expected and has to use all his dirty tricks to try and win. Or perhaps the plotline could involve Broly being captured by Frieza's forces, and then Broly breaks free and goes on a rampage against Frieza and his minions.
One popular Goku and Frieza fanfiction might be those that explore their unlikely alliance. For example, a story could be about them teaming up against a greater threat in the Dragon Ball universe. In these fanfictions, the authors often play with their characters' personalities. Goku's pure - heartedness could contrast with Frieza's devious nature, creating interesting plot dynamics.
It could develop through mutual admiration for each other's power. Goku is always looking for strong opponents to test himself against, and Female Frieza is no slouch in the power department. As they spar and train together, they might begin to respect each other more. This could lead to a friendship where they exchange fighting techniques and stories of their battles. Over time, this friendship could deepen into a more meaningful relationship where they trust each other completely.
One of the main themes is the clash of generations. Goten represents the new generation of Saiyans while Frieza is from an older, more menacing era. This creates an interesting dynamic. Survival is also often a theme, as Goten has to fight to survive against Frieza's brutal attacks. Additionally, the theme of justice can be seen, where Goten is fighting for what he believes is right against Frieza's tyranny.