The two main characters are obviously Severus Snape and Harry Potter. Severus is the one who adopts Harry, changing from his usually cold and aloof self to a more caring and protective figure. Harry is the abused child who gets a new chance at a better life under Severus's care.
One interesting plot could be Severus initially struggling to connect with Harry due to their past differences. But as he gets to know the extent of Harry's abuse, he becomes fiercely protective. He starts teaching Harry advanced magic privately, which helps Harry grow both in confidence and power.
He would become more nurturing. Usually, Severus is seen as cold and aloof, but with Harry in his care, he'd have to show more warmth. He might still be strict, but it would be out of love for Harry's well - being rather than just being his usual harsh self.
One possible plot could be that Severus discovers the extent of Harry's abuse at the Dursleys. He decides to take Harry in out of a sense of duty or perhaps a hidden soft spot for the boy. He then has to teach Harry about magic in a more personal and nurturing way, different from Hogwarts. They might also face opposition from the wizarding community who question Severus' motives.
One common theme is redemption. Severus, who has had a complex and often negative relationship with Harry in the original series, gets a chance to redeem himself by protecting and caring for Harry. It shows that he can be more than just the strict and often cruel teacher.
One popular one is 'A Father's Love'. In this fanfic, Severus discovers Harry's abuse and takes him under his wing. He teaches Harry potions and helps him deal with the trauma of his past in a very heart - warming way.
Severus' character undergoes a major transformation. He begins to value relationships more, especially his newfound father - son relationship with Harry. He may start to interact more with the other students in a less intimidating way because he realizes that being harsh all the time isn't good for anyone, especially Harry. He also becomes more involved in the non - potions aspects of Harry's life at Hogwarts, like helping him with his other studies or dealing with bullying from other students. This shows a side of Severus that was previously hidden, a side that cares deeply for someone other than himself.
One possible plot could be that Snape, out of a sense of guilt or a newfound understanding of Harry's situation, decides to take him in. Snape would have to deal with Harry's grief over his parents and his own complex feelings towards the boy. He might start to teach Harry magic in a more personal and different way than at Hogwarts, leading to a unique bond between them.
Snape's personality would likely soften. He'd have to be more patient and understanding. Instead of just being the strict and often sarcastic Potions master, he'd become more nurturing. He'd still have his sharp edges, but around Harry, he'd show more kindness and care as he takes on the role of a guardian.
Severus is a very observant character. He may notice that Harry has a lack of certain basic skills or knowledge that a normal - cared - for child would have. For instance, Harry might not know how to handle simple social situations in a healthy way or might be overly defensive. This could lead Severus to suspect that Harry's home environment, where he should have learned these things, is not a healthy one and that he might be suffering abuse.