Perhaps James Sirius Potter is on a quest to clear his father's name in some way. He approaches Snape thinking he can get some answers. Snape, on the other hand, has his own grudges and secrets. Their meeting would then be a battle of wits and emotions as they navigate through the past and present issues.
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.
In a fanfiction scenario, James Sirius Potter could be a bit of a troublemaker. When McGonagall meets him, she would have to decide how to deal with him. She could choose to be lenient, seeing the potential in him, or she could be very firm. However, as she gets to know him better, she realizes that he has a unique charm and talent, much like his father. And she could start to encourage him to use his skills in a positive way, perhaps guiding him towards a particular area of magic study that she thinks would suit him.
In the fanfiction, they might have a heartfelt reunion. They could share all the things they didn't get to say before. Maybe they'd talk about their friends left behind, like Remus and Harry. They'd probably also recall their adventures at Hogwarts, from the pranks they played to the battles they fought together.
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.
In such a fanfiction, Albus Potter might initially be intimidated by Snape's reputation. But he could gradually discover Snape's hidden qualities. Maybe Snape would become a mentor - like figure to Albus, guiding him in magic that he couldn't learn from others.
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.
Perhaps Snape could help Albus Severus come to terms with his family legacy. Albus Severus is named after two great wizards, Albus Dumbledore and Severus Snape. Snape could share his own experiences of being in the shadow of great names and how to carve out one's own identity in the wizarding world. This encounter could be a very emotional and character - building moment for Albus Severus.
Well, Albus could finally understand Snape's true nature. Maybe he discovers the sacrifices Snape made for his family. He might apologize for any wrong assumptions he had about Snape in the past.
In a fanfiction where Petunia meets Sirius, it could be a very interesting encounter. Sirius, being a wizard from the wizarding world, might shock Petunia at first. He could show her some simple magic, like making a flower bloom, which would both terrify and fascinate her.
In the fanfiction, when James meets Lily's family, there could be a lot of different scenarios. For instance, if Lily has a younger sibling, James might end up playing with them and showing his fun side. Her family could be initially skeptical of him, especially if they know about his past pranks. But as they see how much he cares for Lily, they start to warm up to him. He may also share his future plans with them, which includes Lily of course, to show his seriousness and commitment.