A common theme is the adjustment to married life. They have to learn to live with each other's habits. Another theme is family. They might think about having children or dealing with their extended families.
One theme that frequently shows up is the exploration of their personalities within the marriage. Trunks might be more reserved in some fanfictions, while Pan is more outspoken. Their marriage then becomes a journey of understanding and complementing each other. There can also be themes related to cultural differences, as they come from different backgrounds within the Dragon Ball universe, and how they navigate those differences in their married life.
One common theme is friendship. Since Pan and Trunks are from the same group of Saiyans, many fanfics explore how they support and rely on each other. For example, they might face a powerful enemy together and their friendship is what gets them through.
One common theme is adventure. They might go on quests together and during that, their relationship blossoms. Another is the idea of Trunks helping Pan unlock her hidden powers, which leads to a closer bond.
One common theme could be adventure. They might go on adventures together and their relationship develops during those experiences.
Growth and self - discovery are also prevalent themes. The characters of Pan and Trunks are still young and have a lot to learn about themselves and their powers. In many 'pan x trunks fanfic', they go through journeys that help them understand themselves better, and this is often intertwined with their relationship with each other.
One common theme is growth. They both grow as characters, whether it's in terms of their fighting abilities or their emotional maturity. For example, in many fanfictions, Trunks helps Pan to become a better fighter and Pan helps Trunks to open up more emotionally.
The theme of adaptation is very common. Peter Pan has to adapt to living with a partner, sharing his space, and making decisions together. Also, the theme of love against all odds can be seen. Given Peter's wild and free nature, it seems unlikely for him to settle down, so when he does get married in fanfiction, it's often about a love that is so strong it overcomes his natural instincts. In addition, some fanfictions explore how his marriage affects the other characters in Neverland, like the Lost Boys, Tinker Bell, etc.
Often, there's the theme of family influence. Given their family backgrounds in the Dragon Ball Z world, how their families' legacies affect their relationship is a big part of many fanfictions. For example, Trunks being Vegeta's son and Pan being Gohan's daughter, their families' reputations and powers play into the story. Also, the theme of friendship evolving into something more is quite common. They start as friends or comrades and then develop deeper feelings for each other as the story progresses.
One common theme could be the exploration of family and relationships. How their friends and family react to the pregnancy and how they adjust to the new situation.
Most of their friends would be very supportive. However, there might be a few who are jealous. Some might be envious of the love they share. But overall, their friends would throw a huge celebration. Bulma would use all her resources to make the wedding a grand affair. And the Z - Fighters would put aside their training for a while to celebrate with them. There would be a lot of laughter, stories shared, and of course, some friendly sparring during the pre - wedding celebrations.
Well, a plot twist could be that Pan discovers she has some special power right before the wedding. This power might be something that no one in the Saiyan family has had before. It could make her question her identity and whether she is worthy of being with Trunks. Or perhaps Trunks is forced to go on a sudden mission and is presumed dead, but then returns just in time for the wedding in a very unexpected way.