In this fanfiction, Gohan might learn valuable life lessons from Grandpa Gohan. Maybe Grandpa Gohan would teach Gohan some old - fashioned martial arts techniques that have been forgotten over time.
Caulifla could be a great choice. She's strong - willed and has a passion for fighting. Her energetic personality could create an interesting dynamic with Gohan, who is more reserved in some ways.
The theme of self - discovery is often present. The female Saiyan may be trying to figure out her place in the universe, and Gohan, with his own experiences, helps her. Or Gohan himself might be on a journey of self - discovery with the female Saiyan as a catalyst, especially in terms of his Saiyan heritage.
Gohan's character often develops by learning to control his Super Saiyan 3 power better. He might start out as a bit reckless with it and then grow more disciplined. For example, he could initially use it to show off but later realize the responsibility that comes with such great power.
One idea could be Gohan in his Super Saiyan 4 form facing a new, powerful enemy from another dimension. He could struggle at first to control the raw power of this form while also trying to protect his friends and family. Maybe this new enemy has the ability to nullify the Saiyan's energy attacks, forcing Gohan to rely more on his martial arts skills that he learned from Piccolo.
In some fanfictions, an OC Saiyan could be a time - traveler who meets Gohan at different points in his life. This OC Saiyan could change the course of Gohan's life in small ways, like helping him to train harder during his childhood or giving him advice during the Cell Games that he didn't receive in the original story. This would create a whole new timeline of events for Gohan and the Dragon Ball universe.
In a fanfiction, Gohan as Super Saiyan 3 could be involved in a time - travel adventure. He travels back to a crucial point in Dragon Ball Z history and has to use his Super Saiyan 3 powers to change certain events. This could lead to a whole new timeline where things are different. For example, he might be able to prevent the destruction of Planet Namek or save some characters who originally died.
I'm not aware of any such fanfiction. The relationship between Grandpa Gohan and Son Goku in the original story is one of love and mentorship, so this kind of dark and negative portrayal in fanfiction is not common that I know of.
Goku and Grandpa Gohan's interaction could be full of wisdom - sharing. Grandpa Gohan was a wise man, and he would pass on more of his knowledge to Goku. Goku, in turn, would tell Grandpa Gohan about all the new friends he has made and the different planets he has visited. They might also spar a bit, just like in the old days, with Grandpa Gohan giving Goku some pointers.