Kakashi would be intrigued. He'd probably study Naruto more closely to see how this new influence affects his growth as a ninja. He might also try to find ways to help Naruto blend Kratos - inspired skills with his existing ninja abilities. Kakashi would be open - minded about it, knowing that new sources of inspiration can lead to great power.
Percy's reaction would be a mix of confusion and fascination. The world of Kratos is so foreign to him, with different rules and a much darker tone. However, he would also be drawn to the hero's journey that Kratos undertakes in the fanfiction, comparing it to his own journey as a demigod.
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.