In fanfiction, when James Sirius Potter meets the Dursleys, he might be shocked by their coldness. He could try to understand why they treated Harry so badly. Maybe he'd confront them about their past actions, or he might just observe them quietly to see what kind of people they really are.
He might interact with suspicion at first. Given what he knows about how they treated his father, he'd be on guard. But then he could be polite just to see how they respond.
One possibility could be that Snape meets James Sirius Potter in a Hogwarts flashback scenario. Maybe James Sirius Potter discovers some old memories or secrets related to Snape through a magical object. This could lead to a whole new understanding of Snape's character for him.
One possible scenario could be that McGonagall meets James Sirius Potter in a Hogwarts corridor. She might be reminded of his father, James Potter. She could give him some sage advice about living up to the Potter name and the importance of using his talents for good, just as his father did in his own way.
In this fanfiction, perhaps James Sirius Potter could learn some of the classic pranks the Marauders were famous for. He might get into all sorts of adventures, following in their footsteps and causing a bit of chaos at Hogwarts just like they did.
In fanfiction, James Sirius Potter's birth is often depicted with a lot of excitement and anticipation. Writers might describe the Potter family's joy, and perhaps the presence of friends like the Weasleys during this special time.
One popular type of fanfiction about James Sirius Potter might be his adventures at Hogwarts. Writers could explore his relationships with his friends and family, like how he deals with the legacy of his famous father, Harry Potter. Maybe he gets into some mischief in the same way his father did, but also has to face new challenges specific to his own time at the school.
The main character is James Sirius Potter. As for the Marauders, James Potter would be important as he's James Sirius Potter's father. Sirius Black would bring his wild and rebellious nature into the story. Remus Lupin with his kind heart and werewolf secret could add depth. And even Peter Pettigrew, despite his later actions, would be part of the group dynamic in the fanfiction. There might also be other characters from Hogwarts during the Marauders' time or James Sirius Potter's time who interact with them.