In the time travel fanfiction, their relationships could become stronger. Traveling through time together means they rely on each other more. Danny, as the more experienced one in dealing with the supernatural, would protect Sam and Dani. Sam, with her intelligence, would be the one to figure out time - travel puzzles, making Danny and Dani admire her more. Dani, being their daughter, would grow closer to her parents as she sees them in different historical situations and they work together to overcome difficulties.
Their relationships would develop in a complex way. Imagine they travel to a time where Danny's powers are seen as evil. Sam would have to be the one to support Danny emotionally, and Dani would learn about the hardships her father has faced. In another time, Dani might get separated from them for a while. This would make Danny and Sam frantic with worry, and when they are reunited, their bond would be even stronger. Also, as they interact with different versions of people from different times, they would have conversations about family values and love, which would further shape their relationships in the fanfiction.
Sam would likely develop in terms of becoming more responsible and maternal. As the pregnancy progresses, she'll become more in tune with her body and the needs of the unborn Dani. Danny would probably become more protective and grow in his ability to support Sam, both emotionally and practically.
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.
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.
In the lead - up to the wedding, they would have to work through a lot of issues together. Sam might help Danny come to terms with his role as a half - ghost in a more positive way. And Danny would support Sam in dealing with her family's concerns. This would strengthen their bond and make their relationship more mature and stable for the wedding and beyond.
One possible story could be that Dani travels back in time to prevent a major disaster in the Danny Phantom world. Maybe she goes back to the time when the portal was first opened and tries to stop it, which would change the entire course of events in the series.
Vlad's relationship with both Danny and Dash would be complex. He might initially view Dash as a tool to get to Danny, using Dash's aggression towards Danny to his advantage. As for Danny, Vlad has his own twisted reasons for wanting to control or defeat him. However, as the story progresses, Danny could start to see through Vlad's manipulations and try to turn Dash against Vlad too. So, the relationships would be in a constant state of flux, with power dynamics and personal growth playing important roles.
Perhaps their relationship develops in a way that they become more like partners in crime. They could use the Christmas chaos to their advantage. For example, if there's a mean - spirited Christmas spirit causing trouble in town, they work together to stop it. Danny uses his powers and Sam uses her wits and knowledge, and this shared experience makes their relationship grow in a new and exciting way.
The plot could center around the emotional journey. Sam may experience a range of emotions from joy to fear. Danny could be there to comfort and encourage. They might also face difficulties such as financial concerns. For example, they'll need to think about buying baby stuff, finding a bigger place if needed. And as the pregnancy progresses, they'll have to start thinking about Dani's future, like education and what kind of life they want to provide for the child.
Often, in fanfiction, conflicts play a big role in their relationship development. Maybe there's a new character who is interested in Danny and Sam gets jealous. This jealousy makes her realize her true feelings for Danny. And Danny, in turn, sees how much Sam cares and his feelings for her intensify. It's a common trope that helps to move their relationship forward.
Danny would probably be heartbroken. He really cares about Sam, so finding out she cheated would be a huge blow. He might go into a state of denial at first, not wanting to believe it.