At first, it's likely to be tense. Harry has years of seeing Snape as a bully. But as they start living together, they begin to understand each other. Snape might show his more vulnerable side to Harry, like his memories of Harry's mother. Harry, in turn, starts to respect Snape's knowledge and sacrifice. Eventually, they develop a bond like a father - son relationship.
If Snape adopts Harry after the war in fanfiction, it could be a chance for Harry to heal. Snape, despite his gruff exterior, might be able to provide a stable home environment for Harry. Harry would be exposed to Snape's vast knowledge of the wizarding world, including dark magic defenses. They might also have some interesting conversations about Hogwarts, the Order of the Phoenix, and Voldemort. Harry could grow into a more well - rounded wizard under Snape's tutelage.
In certain fanfictions, Harry could be the one to reach out to Snape. He might feel a sense of indebtedness towards Snape for his sacrifices. Snape, initially resistant, could eventually warm up to Harry's attempts at reconciliation. This could lead to a very different dynamic from their pre - war relationship, with them learning from each other and forging a new path in the post - war wizarding world.
In some fanfictions, Harry might come to understand Snape better and they could develop a grudging respect for each other. Harry realizes all that Snape sacrificed in the war and how he was on the good side all along.
One possibility is that they team up to fight against the remnants of the dark forces that are still lurking in the shadows. Harry's courage and Snape's knowledge would make them a formidable duo. They might travel to far - flung places in the wizarding world, from hidden valleys to enchanted islands, in search of these threats and ways to eliminate them. And along the way, they would have to learn to trust each other more and more, which would be a huge character development for both of them. This would also expose them to different magical cultures and practices that they hadn't encountered before, adding more depth to their own magical abilities.
On the other hand, it could also lead to a strange kind of understanding. Maybe Harry realizes that Snape is under a great deal of pressure and that the punch was a momentary lapse. This could make Harry more empathetic towards Snape, although he might still be angry about being punched.
There could be a scenario where Snape is initially hesitant to interact with Hermione. But she is persistent. She tries to understand his past and his pain. As she breaks through his walls, they start to have a more open and honest communication. They might exchange stories about their time at Hogwarts during different eras, and Snape could finally have someone who truly understands him, at least to some extent, in Hermione.
Some fanfictions show Harry and Snape having very tense interactions. Even though the war is over, the years of hatred and misunderstanding don't just disappear overnight. Snape might still be sharp - tongued with Harry, and Harry might be on edge around Snape.
One popular theme is redemption. Snape was a complex character, and in post - war fanfictions, his relationship with Hermione could explore his journey towards full redemption. Another theme could be the mending of the wizarding world. Hermione, with her intelligence and Snape's deep knowledge of the Dark Arts, could work together to heal the scars of the war. Also, there might be a theme of unexpected friendship or more. Given their differences in the original story, seeing them interact in a post - war setting can lead to some very interesting character - driven stories.
In some fanfictions, Snape might be seen as a mentor figure to Hermione after the war. Since he sacrificed so much and she respects knowledge, he could guide her further in advanced potions or dark arts defense knowledge.