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.
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.
A fanfiction might explore the idea of Bardock seeing Goku's life through a time - space rift. He witnesses all of Goku's battles and the friends he makes. Bardock is filled with pride but also realizes that Goku has a different path than the traditional Saiyan way. This makes him question the Saiyan culture he once knew. Meanwhile, Goku starts to have strange dreams about his father, which leads him to search for more about his Saiyan heritage.
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 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.
It could be a story of redemption for Raditz. He starts off as a bit of a villain, but through interactions with Bardock (either as a memory or some kind of spirit guidance) and Goku's influence, he changes his ways. They could all be training together on Planet Vegeta before its destruction, with Bardock teaching them valuable Saiyan combat techniques and life lessons that shape them into the characters we know.
One possible plot could be that Goku, having achieved new levels of power, somehow travels back in time to meet Bardock. Bardock, initially shocked, quickly realizes this is his son. They could have a sparring session where Bardock sees the full extent of Goku's power and is proud. Then they might sit and talk about Goku's life on Earth, and Bardock could share some of his own past battles and the reasons he sent Goku away.
It could change it a great deal. Goku might learn more about his Saiyan roots earlier, which could potentially make him more in tune with his Saiyan side. This could lead to him training differently or having different goals. For example, he might be more interested in exploring his Saiyan heritage and what it means for his power - up potential.