Well, Goku is a Saiyan, and Saiyans have a strong sense of family deep down, even if they don't always show it. When he meets his parents in this fanfiction, he could initially be in disbelief. But once he realizes it's real, he would embrace them wholeheartedly. He may even start to show off his strength and skills a bit, like a child showing off to his parents. And he would be excited to hear stories about their Saiyan race and how they ended up in the situations they did.
He would be extremely excited. Goku has always been curious about his parents, so he'd probably have a big smile on his face and lots of questions to ask them right away.
Goku's reaction could be a mix of shock and joy. On one hand, he has been on Earth for so long without any real family connection to his Saiyan side. When he sees his parents, it would be overwhelming. He would likely be in awe of his father, Bardock, given his father's reputation as a strong Saiyan. And he would be eager to bond with his mother, who he has never known. He might also feel a sense of belonging that he has been missing all his life.
They likely have a loving relationship. As Saiyans, they would have a bond based on their race and their shared goals, perhaps related to the Saiyan pride and survival.
His father might be extremely proud. After all, Goku has achieved so much, like protecting the Earth multiple times. He would look at Goku with admiration for his strength and kindness.
Gohan would be really surprised, but being the kind - hearted person he is, he would try to understand and help out. He could offer to train with them in a more gentle way to keep them fit during the pregnancy. Piccolo would be more of a silent observer, but still be there in case of any threats.
The reaction among fans would be quite mixed. Some die - hard fans of the original series would be appalled as they have a clear image of ChiChi and Goku's relationship. They would see this type of fanfiction as a perversion of the original concept. On the other hand, there are those who are more open - minded and might see it as an interesting, if not controversial, exploration of the characters. But overall, the negative reactions would probably outweigh the positive ones.
Goku would be a mix of angry and worried. His Saiyan blood would make him want to rush into battle with Raditz right away. But he also knows how dangerous Raditz is, so he might first try to gather some allies, like Piccolo. He'd be constantly thinking about Gohan and how to rescue him as quickly as possible.
Obviously, Goku is the most important character. Then his parents, Bardock and Gine. Bardock was a powerful Saiyan warrior, and Gine was a kind - hearted Saiyan. There might also be other characters like Goku's friends on Earth who could be involved in the story in some way, for example, they could be witnesses to the reunion or help Goku's parents adjust to life on Earth.