Well, in this fanfiction, they could be on a quest to save their own time. They might travel to different time periods to gather items or knowledge necessary to prevent a disaster in their present. They could also make new friends along the way in different times who help them in their mission.
They might have adventures like exploring ancient civilizations. Maybe they meet historical figures and learn from them. For example, they could meet Leonardo da Vinci and watch him paint. Or they could end up in a prehistoric era and see dinosaurs.
Danny's adventurous spirit would make him eager to jump into different time periods and experience new things. However, Sam's more reserved nature would ensure they think about the consequences first. For instance, when they come across a strange time - based phenomenon, Danny might want to rush in while Sam would want to study it more before acting.
It could be an evil time - traveling wizard. He's jealous of Danny's powers and wants to steal them. He uses his magic to create all sorts of obstacles for Danny and Sam as they travel through time, trying to prevent them from getting back to their own time.
One idea could be that Danny and Sam accidentally travel back to the age of dinosaurs. They have to figure out how to survive among the giant creatures while also trying to find a way back home. Maybe they discover a time - traveling dinosaur that helps them in some way.
One idea could be that Danny and Sam have kids in the future and their kids inherit Danny's ghost powers. The story could focus on how they learn to control their powers while also dealing with normal kid stuff like school and making friends. It would be interesting to see how Sam, as a mom, guides them through this.
Perhaps in the fanfiction, Danny discovers that there is a threat in the past that could change the future in a very bad way. He, along with Sam and Dani, time - travels to stop it. Along the way, they meet younger versions of their friends and family. Dani starts to understand more about her family's history and her own place in it. Sam has to deal with the differences in the past's social norms compared to their time. And Danny battles villains from the past who are trying to take over the future using the knowledge of time travel they accidentally introduced.
Their relationship might also face some challenges. Maybe in a particular time, Sam's more radical ideas clash with Danny's more cautious approach. For instance, when they travel to a time where there is a strict social hierarchy, Sam wants to immediately start a revolution to change things for the better, but Danny is worried about the consequences this might have on the timeline. However, through these challenges, they could grow to understand each other better.
One idea could be that Danny and Sam travel back to the founding of Amity Park and accidentally change something small that has huge consequences in the present. For example, they might stop the first settler from building in a certain spot, which then changes the layout of the whole town and where ghosts can enter from in modern times.
They might have adventures in a world full of advanced magic technology. For example, they could encounter new spells that are created in the future to deal with different threats. They may also meet their descendants and learn about how their actions in the past have influenced the future generations.
Hermione would start by studying all the new things she could find. Ron would follow Harry's lead most of the time. Harry would use his instincts to figure out who to trust in this new future.
It could be that they are just big fans of the creativity in fanfiction. There are so many different ideas and concepts that come from fans all over the world. It's like a never - ending stream of new stories based on the things they already love, and that's what makes it appealing to them.