At first, Harry might be extremely suspicious. Snape has always been cold and mean to him in the past. He would wonder what Snape's true motives are. Harry is used to being on his own and not relying on Snape for help, so this sudden rescue would be very unexpected.
Harry might be a bit conflicted. On one hand, he is grateful to be rescued from the Dursleys. On the other hand, he has a lot of emotional baggage regarding Snape. He might struggle between his natural inclination to be polite and grateful to his rescuer and his past experiences with Snape that make him hesitant to fully accept Snape's help. It would be a journey for Harry to come to terms with Snape's new role in his life.
Perhaps Snape discovers some dark plot involving the Dursleys that could harm Harry more than he initially thought. The Dursleys were known to be cruel to Harry, and Snape might have found out that they were involved with some Death Eaters or dark magic users who planned to use Harry in a harmful way. So, he decides to rescue Harry to prevent this from happening.
It could make Harry more empathetic. Snape is a complex character, and through his rescue, Harry gets to see a different side of him. This could make Harry more understanding of others' hidden motives and pain. He might start to look beyond the surface when dealing with people, which would be a great development for his character as he faces more complex relationships in the wizarding world.
In the fanfic, Snape might use his knowledge of the Dursleys' house layout. He may enter the house unnoticed, find Harry, and then use a Portkey to quickly get them both out of there. He could also have some sort of charm or potion that he uses to counter any magic the Dursleys might have used to keep Harry there, like a spell - breaking potion. And he may have planned the whole rescue very carefully, choosing a time when the Dursleys are least likely to notice, like in the middle of the night.
The plot twist could be related to Snape's true motives. He might be under an Unbreakable Vow to rescue Harry from the Dursleys. In the process, Harry realizes that Snape is not as bad as he seems. This could lead to a complete change in their relationship. Harry could start to trust Snape, and Snape, in turn, could teach Harry some unique magic that he has never learned before, which is crucial for the upcoming battle against Voldemort.
In a gay romance fanfiction where Snape rescues Harry, the rescue could be both physically and emotionally. Physically, Snape might save Harry from a dangerous spell or a life - threatening situation. Emotionally, it could be Snape rescuing Harry from feelings of isolation or self - doubt. This could lead to a beautiful relationship where they support and love each other, perhaps defying the norms of the wizarding world.
Perhaps Snape uses magic to create a distraction at the Dursleys' place. He could make strange noises or apparitions that scare the Dursleys, and while they are in a panic, he grabs Harry and disapparates. This would be a quick and efficient way for him to rescue Harry.
Snape could initially be skeptical. Given their long - standing enmity, he might not believe that Harry's apology is sincere at first. He might respond with a cold glare or a sarcastic comment, like 'Potter, your apologies are as empty as your head.'
Well, he might be quite reluctant at first. Snape has always had a rather complex relationship with Harry. He might see it as a huge burden and be full of doubts. After all, he has his own grudges and past issues with James Potter, Harry's father. But on the other hand, he also has a sense of duty towards Harry as he was Lily's son. So it's a mix of emotions that he has to deal with.
However, as the story progresses, Harry may start to understand the reasons behind Snape's actions. He could become more resigned and accept the punishment as a part of his growth. He might use the experience to become more cautious in his actions and more respectful of the rules.
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.