One plot idea could be that Bardock, in some way, gets to see the future Goku achieves. Maybe through a time - warp or a prophetic vision. Another could be a story where Baby Goku is sent on a special mission, and Bardock's spirit somehow guides him. For example, when facing a really tough enemy, Baby Goku hears Bardock's voice in his head giving him advice on how to fight.
One way is to make Bardock a sort of guardian angel figure for Baby Goku. He's not physically there but can influence Goku's life in small ways. For example, he might cause a gust of wind to push Goku in the right direction when he's lost in the forest as a baby. Also, their relationship could be explored by having Bardock's old enemies mistake Baby Goku for Bardock and target him, and then through these encounters, we learn more about how Bardock and Goku are related.
At first, it might be tense. Bardock is a hardened Saiyan warrior from a different era, and Goku has grown up on Earth with a very different set of values. But as they start to communicate, they would find common ground in their Saiyan blood. Goku's pure - heartedness could gradually win over Bardock, and Bardock's strength and pride could earn Goku's respect.
At first, it could be a bit rocky. Bardock is used to the harsh Saiyan ways, while Goku has been raised on Earth with different values. But as they spend time together, they start to understand and respect each other. Bardock could become a mentor to Goku, teaching him advanced Saiyan fighting techniques and Goku could teach Bardock about friendship and love.
One possible interaction is that Bardock could spar with Goku and Gohan. He'd test their limits and see how much they've learned about fighting. Another could be Bardock sharing stories of Planet Vegeta with them, which would be really interesting for Goku and Gohan to hear.
In a 'Bardock meets Goku fanfiction', perhaps Bardock is pulled through time and space and lands on Earth during one of Goku's battles. Goku is shocked to see his father but quickly accepts him. Together, they team up against a powerful villain. Bardock shares his Saiyan knowledge with Goku, which helps Goku unlock new powers and defeat the enemy.
One possible plot could be that Goku, through some time - travel or interdimensional rift, meets Bardock in the past. Bardock could initially be suspicious of Goku, not knowing he's his son. But as they interact, Goku might show some of his Saiyan power and spirit that reminds Bardock of his own. They could then team up against a common enemy, like a powerful alien race threatening Planet Vegeta.
In this fanfiction scenario, it could be an extremely emotional encounter. Goku, who has grown so much in Dragon Ball Super, finally meeting his father Bardock. Maybe Bardock gets to see how his son has not only become a powerful Saiyan but also a protector of Earth. It could lead to some interesting exchanges about Saiyan heritage and the future of the Saiyan race.
Sure, there are. One interesting aspect of 'Bardock x Goku fanfiction' could be the exploration of their connection through the Saiyan bloodline. Since Bardock was Goku's father, some fanfictions might delve into how Goku might have been different if he had grown up with his father around. Maybe there could be stories where Bardock survives and trains Goku in the Saiyan ways from a young age, which would be a really cool and different take on the Dragon Ball story.
A frequent theme in 'Bardock x Goku fanfiction' is power. How Bardock's power or knowledge could be transferred to Goku. Also, redemption can be a theme. Maybe Bardock has to make up for past mistakes through helping Goku. And of course, the theme of survival. Stories where Bardock somehow survives and his presence changes Goku's life in the Dragon Ball universe.