Piccolo might also be a savior. He has a soft spot for Gohan since they trained together. He could use his strategic mind and powerful attacks to outwit Raditz and rescue Gohan. Maybe he teams up with Goku for an even more epic rescue mission.
In a 'Gohan kidnapped by Raditz' fanfiction, the plot could involve Raditz trying to turn Gohan against his family. He could expose Gohan to the cruel ways of the Saiyan race that Goku has somewhat distanced himself from. Raditz might show Gohan visions of the Saiyan's former glory and try to convince him that his human family is holding him back from achieving true power.
One plot idea could be that Gohan's friends, like Krillin and Bulma, team up to rescue him. They might use some of Bulma's inventions to track Raditz. Another idea is that Gohan manages to outwit Raditz during the kidnapping. Maybe he uses his hidden power to escape Raditz's clutches briefly and leaves a trail for his father Goku to follow.
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.
In a 'Gohan Raised by Vegeta' fanfiction, Gohan's personality would likely change a great deal. Vegeta being his mentor would mean a strict and no - nonsense upbringing. Gohan would probably be more confident in his Saiyan heritage. His fighting style could be a blend of Vegeta's elegance in combat and his own natural potential. Also, the relationship between Gohan and other characters like Piccolo or Chi - Chi would be very different. With Vegeta's influence, he might be more rebellious against Chi - Chi's wishes for him to focus on academics.
One possible plot twist could be that Gohan becomes more powerful than Vegeta much earlier than expected. This would create an interesting dynamic as Vegeta would have to deal with his student surpassing him. Another could be that Gohan discovers a new Saiyan ability that Vegeta was unaware of, which could change their relationship and how they approach training.
If Raditz survived in fanfiction, he would likely have a complex relationship with Goku. He might start to see the value in Goku's way of life. Goku could try to reform him, and Raditz could slowly become a more positive force in the Dragon Ball Z universe.
A good Raditz story should focus on his Saiyan heritage. For example, showing how his Saiyan instincts play out in different situations, like when he's facing a tough enemy or making a decision about whether to show mercy or not.
If Raditz turned good, it might have led to more complex character dynamics and interesting plot developments. He could have learned from his mistakes and become a valuable ally.