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.
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.
Well, it could be about a lot of things. Maybe it's a fan - created story where Chilled, Bardock, and Goku are all involved in some sort of adventure or conflict. It might explore their relationships, like perhaps a scenario where Goku has to face off against Chilled while Bardock's legacy or influence somehow plays a part.
Another theme is power transfer or inheritance. Some fanfics might have Bardock passing on some hidden power or knowledge to Goku. This could be related to their Saiyan abilities or some special technique that only their family line can access. There is also the theme of redemption in some cases. If Bardock is brought back in a fanfic, he may seek to atone for his past actions through his relationship with Goku.
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.
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.
In a 'Bardock meets Goku' fanfic, the plot might involve Bardock being brought back to life by the Dragon Balls. He then sets out to find Goku. When they meet, Goku is initially confused but then realizes it's his father. They could then train together and Bardock could teach Goku some long - lost Saiyan techniques. It could also be a more emotional meeting where they talk about Goku's past and his mother.