Snape's character often develops from a cold and aloof figure to a more caring and father - like one. He starts to see Harry not just as James Potter's son but as an individual he is responsible for. His protective instincts grow, and he becomes more patient. For example, he might initially snap at Harry for small mistakes but over time, he learns to guide him gently.
The relationship would start off rocky. Snape would be resistant to Harry's kindness as he has always seen Harry as James Potter's son. But Harry's persistent efforts to understand and help Snape would gradually break down Snape's walls.
In this fanfiction, the story could start with Harry finding Snape in a very vulnerable state after the Battle of Hogwarts. Harry feels a deep sense of guilt for how Snape was treated throughout his life. So he decides to adopt him. At first, their relationship is awkward. Snape is still his old sarcastic self, but Harry is determined. As time passes, they discover they have a lot in common. They both lost their parents at a young age, and they both had to face great challenges. This newfound understanding leads to a transformation in their relationship. Harry helps Snape to come out of his shell of bitterness, and Snape teaches Harry more about the Dark Arts in a controlled and ethical way so that Harry can better protect the wizarding world in the future.
A great plotline might be that Snape adopts Harry secretly at first. Harry starts to notice some changes in his life, like getting better study materials and more personal attention in his magical education. As time goes on, Snape has to face his own demons while raising Harry. He might struggle with his past hatred for James Potter while seeing James in Harry. At the same time, Harry could be trying to figure out why Snape is being so nice to him all of a sudden, which could lead to a journey of self - discovery for both of them.
In such a fanfiction, Harry might see the potential in young Severus that others overlooked. He could protect Severus from the bullies at Hogwarts. Harry, having experienced his own share of hardships, would understand Severus's situation to some extent and try to give him a better childhood, perhaps even guiding him to use his magic in a more positive way.
A really unique plot could be Snape adopting Harry during a time when Voldemort is still a threat. Snape has to balance protecting Harry from Voldemort's followers and also from the prejudice within the wizarding community. He might train Harry in Occlumency more intensively, and in the process, they develop a deeper understanding of each other. Harry starts to see Snape not as the mean professor but as a complex person with his own traumas and reasons for his actions.
Snape's character changes in his relationship with others too. He becomes more involved with the Hogwarts community as he is now responsible for Harry. He might start to collaborate more with other teachers, like McGonagall, who he previously had a rather cold relationship with. His attitude towards the students also changes as he realizes that they are just kids trying to find their way, much like Harry. This is a big shift from his usual strict and often unforgiving self.
Severus could become more confident. With Harry's support, he may not be as shy or withdrawn as in the original story. He might be more open to making friends outside of Slytherin.
If Severus Snape adopted baby Harry Potter in fanfiction, it would completely transform the story. Firstly, Harry would grow up in a very different environment. Snape, being a strict and complex character, would likely raise Harry with high expectations in academics, especially in Potions. Harry might become more introverted under Snape's influence as Snape isn't the most sociable person. Also, Snape's knowledge of the Dark Arts could either protect Harry better or put him in more danger, depending on how Snape chose to use it in Harry's upbringing. The relationship with the other characters would be different too. For example, Harry's relationship with the Weasleys might not be as strong as in the original story since he would be growing up in a more isolated environment with Snape.
Snape's parenting style would likely be strict. He is a no - nonsense person, so he would expect Harry to follow rules precisely. He would probably be very demanding when it comes to Harry's studies, especially in Potions. However, Snape also has a deeply emotional side, so he might be protective of Harry in his own way, though he would rarely show it outwardly.