One great Bardock in Dragon Ball Z fanfiction is often depicted as a fearless and noble Saiyan. He is shown as a warrior who, despite the cruel nature of the Saiyan race at that time, had a sense of honor. In some fanfictions, he manages to break free from the control of Frieza in more creative ways than in the original story, making his character even more complex and interesting.
Well, one aspect of Dragon Ball Super Bardock fanfiction could be exploring his backstory further. Maybe delving into his early days on Planet Vegeta and his relationships with other Saiyans. It could also show his potential power growth that we didn't see in the original series.
A popular version of Bardock in fanfiction is the one who has a premonition of the destruction of the Saiyans much earlier. This Bardock then tries to take actions to prevent it, like gathering other Saiyans who might be sympathetic to his cause. It makes him a hero figure right from the start, rather than just a victim of Frieza's wrath as in the original story.
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.
One idea could be that Bardock lives and he manages to escape Frieza's planet - destroying attack. He then travels through space, gathering power and knowledge. Eventually, he could return to Planet Vegeta as a much stronger warrior and lead a rebellion against Frieza. This would completely change the course of the Saiyan history in the Dragon Ball universe.
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.
The 'what - if' scenario of Bardock becoming a main character instead of Goku. This allows for a whole new perspective on the Dragon Ball universe. We could see Bardock's take on dealing with the various villains and his own moral code in handling different situations.
One interesting 'Dragon Ball Z Bardock' fanfiction could be about Bardock surviving and coming back to change the course of Saiyan history. It might explore his relationships with other Saiyans in a new light, like how he'd interact with Goku differently.
There are some fanfics that focus on Bardock's pre - destruction memories and how they might influence his actions if he were to come back. For example, a story could explore how his love for his family and his hatred for Frieza's tyranny would drive him to train Goku in a different way. He might pass on some of the ancient Saiyan techniques that were lost over time. This could lead to Goku achieving new forms or powers much earlier in the story, which would have a huge impact on the battles against the likes of the Saiyans, Frieza, and the Androids.