Well, this fanfic could be quite interesting from a character - development perspective. If Cell kills Gohan, it could change the entire dynamic of the Dragon Ball world. For example, Vegeta might be forced to step up in a different way, or the Z - fighters might have to completely reevaluate their strategies. It might also show a different side of Cell, perhaps a more menacing and victorious side that we haven't fully seen in the original series.
Well, there's a fanfic called 'Trunks' Time - Travel Tales' that's really good. It plays around with the concept of Trunks' time - traveling in a very creative way. Then there's 'Future Trunks' Love Story' which, as the name suggests, focuses on his romantic relationships. Also, 'The Legend of Future Trunks' is a must - read as it expands on his character and his place in the Dragon Ball universe.
One possible theme could be the fragility of life. Even a powerful fighter like Gohan can be killed, showing that no one is invincible. Another theme might be the concept of revenge. If Gohan is killed by Cell, other characters could seek revenge against Cell.
He becomes more resourceful. In his own time, he's used to a certain set of circumstances. But during time travel, he has to adapt quickly to new situations and find ways to use the resources available in the past. For example, he might have to figure out how to use different senzu beans or power - up techniques that are new to him.
One common theme is time-travel. Since Trunks is known for his time - traveling adventures, many fanfictions explore this aspect further, like dealing with the consequences of changing timelines.
She can be quite independent. In fanfic, female Future Trunks is usually shown as someone who can make her own decisions and follow through with them. She doesn't rely on others easily and is confident in her abilities. She might go on solo missions to save the day, which shows her self - reliance. Moreover, she may also possess a unique sense of style that sets her apart from other characters in the Dragon Ball universe, which adds to her charm in the fanfic world.
Definitely their strong bond. They have been through so much together, so highlighting their loyalty and trust for each other is great. Also, their different fighting styles can add action - packed scenes. For example, Gohan's more methodical and strategic approach against Trunks' more impulsive and aggressive style.
You need to do a lot of research. Watch Dragon Ball Z to fully grasp Future Trunks' character traits and his world. And of course, be familiar with the MLP series. When writing, focus on the character development. Let the two different sets of characters grow and change as they interact with each other. Maybe Trunks becomes more in touch with his softer side through the influence of the ponies, and the ponies become more confident in facing danger because of Trunks.