For Harry, saving Snape could make him more empathetic towards Snape's past actions. He might start to understand the complex web of loyalties that Snape was caught in. It could also make Harry more confident in his ability to make moral decisions independent of others' opinions.
Snape, on the other hand, would be indebted to Harry. This could lead to a complete shift in their relationship. Snape might start to see Harry as a true hero and perhaps even mentor Harry in some of the darker magics that he has knowledge of, but in a more positive way. Their relationship could transform from one of animosity to a grudging respect and then to a more positive mentor - mentee dynamic.
One motivation could be Snape's sense of duty as a teacher. Despite his dislike for Harry in some ways, he still has an obligation to protect the students. So, when he sees Lockhart endangering Harry, he steps in.
Well, it could be possible if Harry discovers Voldemort's plan to kill Snape in time. Maybe Harry uses his invisibility cloak to get close to Voldemort undetected and then uses a powerful spell to stun or deflect Voldemort's attack aimed at Snape.
The Dursleys might be left in a state of shock and confusion. Since they have been so mean to Harry, they could be worried that the wizarding world will come after them for revenge. But since they are Muggles, the wizarding world may just leave them be, but they will always live in fear of the unknown.
Yes, there are some fanfictions with such out - of - the - box concepts in the Harry Potter fanfiction community. However, these are not in line with the original story's canon.
In fanfiction, Snape saving Harry often showcases a complex side of Snape's character. It might be a redemption arc for him, as in the original series, Snape had a very ambiguous relationship with Harry. In these fanfictions, it could be due to his love for Lily that he finally decides to fully protect Harry, which is a very interesting take on his character.
One possible plot twist could be that Snape saves Harry in a very public way, which shocks everyone in Hogwarts. Maybe Umbridge was about to use an illegal and extremely harmful spell on Harry during a public 'interrogation' session, and Snape steps in at the last moment, revealing some long - hidden information about Umbridge's true nature that even Dumbledore wasn't fully aware of.
Another possibility is that Snape uses his position as a teacher. He might threaten Lockhart with the consequences of harming a student. Given Snape's intimidating presence and his own power within the school, Lockhart would be afraid to cross him. Snape could also call for other teachers to help, making it clear that he won't let Lockhart get away with any harm to Harry.
Snape could also be acting out of a sense of justice. Lucius was a Death Eater, and Snape, despite his own past as a Death Eater, had turned against Voldemort. Saving an innocent, especially Harry's daughter, from Lucius would be in line with his new allegiance to the side of good.
Snape's character may develop in a way that shows his loyalty to Dumbledore and the greater good in a more obvious way. Saving Harry from Umbridge, who represents the Ministry's overreach and corruption, could be seen as Snape firmly taking a stand on the side of what's right. It could also make him more conflicted internally as he has to balance his role as a double - agent and this new - found 'protector' role of Harry, which in turn would add more depth to his already complex character.
Yes, it could be possible in fanfiction. Fanfiction allows for wild reinterpretations of the source material. Maybe there could be a story where a dark wizard in the past manipulated their family trees so that Harry, Snape and Voldemort are unknowingly brothers. It would make for a very interesting plot, full of drama and conflict as they are on different sides in the original story.