Often, a theme is Goku's growth in terms of his emotional intelligence when dealing with his harem. He's used to being a fighter, but in these fanfictions, he has to learn about love and companionship. Also, there's the theme of teamwork among the harem members and Goku when they face challenges together, which is quite different from the solo battles Goku is known for in the original series.
One common theme is the exploration of Goku's relationships outside of his usual fighting and training. Another is the development of the female characters in the harem, showing their unique personalities and how they interact with Goku.
Love and redemption can also be common themes. Sometimes the harem members help Goku Black to find a new path or redeem himself through their love. It adds an interesting layer to his character.
One common theme could be the exploration of different relationships. For example, Goku forming strong bonds with multiple characters. Another might be the growth of Goku not just as a fighter but also in his emotional and social interactions within the harem. Also, there could be themes of friendship and loyalty among the members of the harem.
Many Goku and Vegeta fanfictions explore the concept of power. How they strive for more power, what they are willing to sacrifice for it, and how they handle having great power. This can lead to some interesting moral and ethical dilemmas within the stories.
One common theme is the exploration of Goku's vulnerability. Usually, he's seen as this super - strong character, so when he's hurt, it shows a different side of him. Another theme is the bond between him and his friends and family. They often come together to help him when he's injured.
One common theme is the power - dynamic. It often shows how a female character interacts with Goku's extreme power. For example, she might be in awe of it at first and then strive to reach a similar level.
Another theme could be the challenges Goku faces during the pregnancy. Given that he's a powerful Saiyan, being pregnant might bring out different physical and emotional aspects that are not typically associated with his character. It could also involve how he balances his training and the impending arrival of the baby.
A common theme is training. Since Goku is a master of martial arts, many fanfictions focus on him training Caulifla, like in 'Training Days'. It could be about her learning new forms or just improving her basic skills.
One frequent theme is power - up. Given that Goku is known for his various Super Saiyan forms and Caulifla is also a strong Saiyan, fanfictions like to show them achieving new levels of power, either through training or facing a powerful foe. Additionally, the theme of respect is also common. As they witness each other's strength, they gain respect for one another, which is often depicted in these fanfictions.
Power -ups are common. Since both Goku and Naruto are about getting stronger. So in fanfictions, they often find new ways to increase their power, like Naruto learning to use ki or Goku getting some ninja - like abilities.
One common theme is mentorship. Goku often takes on the role of a mentor to Bulla, guiding her in her martial arts journey. Another theme is friendship. They form an unlikely friendship which is explored in many stories.