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.
One idea could be to focus on Bardock's perspective before his fateful battle. Maybe explore his thoughts about his son Goku being sent to Earth and his own impending doom. He could have some premonitions about Goku's future role in saving the 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.
I'm not sure of a specific highly recommended 'Bardock finds Goku' fanfic off the top of my head. But generally, fanfics with a high number of reviews and positive ratings are likely to be good. So when you search on FanFiction.net or AO3, sort the results by the number of reviews or ratings. Check out the ones that seem popular and read the summaries to see if they match what you're looking for in terms of Bardock finding Goku.
A fanfic could explore their relationship through flashbacks. For example, Bardock could have left some sort of message or power for Goku that he discovers later. This would create an emotional connection between them even though they never really met in the original story.
One possible plot could be Bardock's adventures before Goku was born. Maybe it could show how he dealt with the Saiyan politics and his growing concerns about Frieza's rule. This could set the stage for Goku's future battles as his son.
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.