In the 'bardock sees goku as a god' fanfiction, a plot development could be that Bardock's belief in Goku as a god gives Goku new powers or a new level of confidence. This could lead to Goku taking on more dangerous foes. Or perhaps Bardock tries to build a temple or shrine for Goku. There could also be a conflict where some villains try to use Bardock's blind faith in Goku to their advantage by tricking him into leading them to Goku.
Yes, there are likely 'Bardock Kills Frieza' fanfics out there. The Dragon Ball universe has a huge fan base, and many fans like to create alternative storylines. You can try searching on fanfic websites like FanFiction.net or Archive of Our Own.
Well, it could make Bardock more in awe of Goku. He might see Goku as an untouchable being now. This could lead to a more distant relationship at first, as Bardock may feel unworthy to be close. But over time, he could also become a very devout follower or protector of Goku in a new way.
In the fanfic, Bardock might be filled with pride. He could be thinking how his son has grown into such a powerful warrior. After all, Goku has come a long way from being a little Saiyan baby sent to Earth. Watching Goku fight Buu, Bardock might see all the potential he always knew Goku had, finally being fully unleashed.
In the fanfiction, Bardock might be in a state of awe. Goku's fight against Buu is no small feat. Bardock would likely note Goku's ability to keep getting back up, no matter how hard Buu hits him. He might also be thinking about the power levels involved. In his time, the power levels he knew were much lower. Now, seeing Goku take on a foe as powerful as Buu, he'd realize just how much the Saiyan race has evolved, especially with Goku as a prime example.
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.
Then, introduce some shared experiences. Maybe they get trapped in a strange dimension together. In this new and dangerous place, they have to rely on each other's strengths. Goku's physical power and Frieza's cunning could be the keys to their survival. As they go through these experiences, they start to see each other in a new light and their relationship begins to change.
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.