A very laid - back character could become more competitive. The Dragon Ball universe is full of strong - willed individuals competing to be the best. So, the reincarnated character might get caught up in the hype of power - leveling and tournaments, changing their easy - going nature to a more competitive one. They might start training obsessively to keep up with the likes of Goku and Vegeta.
If a character is reincarnated into the Danmachi world, their personality could change due to the new environment. For example, if they were a shy person in their previous life, but in Danmachi, they find that being bold is necessary to survive in the dungeon. So they gradually become more assertive. Also, the new relationships they form in the Danmachi world can influence their personality. If they join a Familia with very outgoing members, they might become more extroverted over time.
Being reincarnated into Master Roshi would be an unexpected but fascinating choice. With the knowledge of modern times, the reincarnated person could introduce new training techniques to Goku and Krillin from the very beginning. They could also use Roshi's pervy side in a more comical way to create some light - hearted moments while still being a respected martial arts master.
If Goku becomes more introverted, the story could change a great deal. His relationships with his friends and family might become more strained as he withdraws from them. For example, he might stop going to Bulma's parties or training with Vegeta as often.
Another theme is changing the story. Reincarnated characters often try to change the events that happened in the original Dragon Ball plot. They might prevent certain deaths or form different alliances. For instance, they could try to stop Vegeta from being evil in his early days in the series.
One great 'Reincarnated Dragon Ball' fanfiction is 'Dragon Ball: Reincarnation of the Strongest'. It has an interesting plot where the main character is reincarnated into the Dragon Ball universe with some unique powers. The story follows his journey as he tries to make a name for himself among the powerful characters already there.
His personality might become more carefree like Luffy's. He would probably be more laid - back and not worry as much about formalities.
Gohan could become more of a leader. With the power of Super Saiyan 5, he would be one of the most powerful beings in the universe. Other Z - fighters might look to him for guidance and leadership. This could bring out a more assertive side of his personality. He would need to step up and make tough decisions for the greater good, which would shape his personality in a more authoritative way.
His personality might become more cautious. As an Eevee, he's smaller and more vulnerable compared to being a human. So he'd probably be more careful when approaching new situations or other Pokémon. But his determination from his previous life as Ash would still be there. He'd still be eager to prove himself and become strong, just in a different way.
Goku's understanding of different universes and races could be deepened in fanfiction. Since Dragon Ball Super introduced the multiverse concept, fanfiction could explore how Goku interacts with and learns from beings from other universes, making him more worldly and less naive in some ways.
Her personality might become more empathetic. As a girl, Percy could be more in tune with the emotions of others around her. For example, she might be quicker to notice when someone is sad or in need of help. In her previous life, she might have been more focused on her own goals and adventures, but now she could be more nurturing.