Well, in this fanfiction, one plotline could be Percy's journey to fully embrace Paul as his father. It might start with small things like learning to trust Paul's advice, and then progress to more significant moments like relying on Paul during a dangerous adventure. Another possible plotline is the family dynamic changes that occur as a result. Percy's mother might be overjoyed to see them getting along so well, but there could also be some jealousy from other relatives. And perhaps there's a plotline where Percy and Paul have to face an external threat together, which cements their father - son relationship even more.
A plotline could revolve around Percy defending his new relationship with Paul to his friends or other family members. Some might not understand why he's so quick to accept Paul as his dad. Also, there could be a plotline where Paul helps Percy through a difficult time, like a school problem or a fight with a bully. This would strengthen their bond and further solidify Percy's decision to call him dad.
Maybe in the fanfiction, Naruto gets injured really badly during a mission. While he is recovering, Kakashi stays by his side constantly, and Naruto realizes the deep care Kakashi has for him, which makes him start to call Kakashi dad. Then, Kakashi helps Naruto train in new ways to get stronger, sharing some of his own hidden techniques and experiences that he hasn't told others before.
It could have a significant impact on Percy's character. For one, he may start to exhibit some of Paul's traits. Maybe Paul is really calm and collected, and Percy begins to pick up on that. Also, it might make Percy more confident in himself. Since he now has a dad figure to look up to, he feels more secure, which reflects in his actions and decisions, like being bolder in facing challenges.
One plotline could be that Percy visits Paul's class as a guest speaker and shares his adventures, amazing the students.
Some common plotlines include Red Hood having flashbacks to his time as Robin and how his relationship with Batman has changed to this new 'father - son' one. There could be a plot where Red Hood is in danger and Batman has to rescue him, which then deepens their bond. Another plotline could be about them having an argument over Batman's methods, but this time with the added layer of their new family relationship. This makes the conflict more complex and emotional, as they are not just mentor and protege but father and son in this fanfiction.
One possible plotline could be Keith growing up not knowing Lotor is his dad. Then, through some series of events in the story, like a battle or a discovery in an ancient ruin, he finds out the truth. This could lead to a lot of internal conflict as he has to come to terms with who his father is, considering Lotor's actions in the original series.
Perhaps in the fanfiction, Paul is in some kind of danger and Bella's choice to be with him is about protecting him. Or it could be that Paul shows Bella a different side of the werewolf world that she finds more appealing than the vampire world she was initially drawn to. It could also involve Bella having to deal with the fallout from choosing Paul, like how it affects her relationships with the Cullens and the other werewolves.
One possible plotline could be that Percy has been betrayed by his closest friend. Maybe this friend revealed a big secret of Percy's, and now Percy feels isolated and heartbroken. He might start to question his relationships and his place in the world.
One possible plotline could be Percy's friends trying to break him out. They might have to overcome various obstacles like guards, traps, and security systems within the prison.
Another plotline could involve Percy facing challenges from the demigod community. Since the world of Percy Jackson has its own rules and norms, his transition might not be easily accepted. His dad could then step in and try to educate the other demigods about acceptance and love. Poseidon might call upon a council of the gods to set an example of tolerance, showing that even in the world of gods and demigods, everyone should be respected for who they are.
One possible plotline could be that Percy has to keep his fatherhood a secret to protect his child from the various threats in the demigod world. Maybe he discovers he has a child from an old relationship and has to balance his new role as a dad while still being a hero.