One common theme is redemption. Snape is often depicted as seeking redemption for his past actions or mistakes. Another theme is unrequited love, mainly his love for Lily. Also, themes of loyalty and sacrifice are prevalent, as Snape's loyalty to Dumbledore and his sacrifice for the greater good are important parts of his character.
One popular 'nice snape fanfiction' is 'The Prince's Tale Redux'. It delves deeper into Snape's character and his relationships in a really engaging way. Another great one could be 'Snape's Redemption', which focuses on his journey towards redemption and how others in the wizarding world start to see him in a new light. There's also 'Snape: A Different Perspective' that offers a unique take on his actions and motives throughout the Harry Potter series.
A common plot twist could be that Snape is actually Harry's real - life protector all along. He pretends to be mean in public but in private, he is training Harry for some greater purpose. Another could be that Snape's niceness is part of a deal he made with Dumbledore that we don't know about in the original story. Maybe Dumbledore asked Snape to be extra nice to Harry to boost his confidence.
Well, it might be that in this fanfiction, Snape has a change of heart due to some event. For example, he could discover some hidden truth about Harry that makes him sympathetic. This new - found niceness can bring out a different Harry too. Harry, who is used to Snape's harshness, might be initially suspicious but then grow to trust Snape. This would then change the way he interacts with the other characters as well, since his relationship with Snape is so central in the original story.
One reason could be that he realizes Harry has a lot of potential and wants to nurture it. He sees that Harry is in a difficult position, being the target of Voldemort, and decides to help him despite their past differences.
In some fanfictions, Snape might share some of his knowledge about the wizarding world's secrets with Harry. Maybe he tells Harry about certain spells or magical artifacts that could help Harry in his fight against Voldemort. This act of sharing knowledge is a way of being nice as it gives Harry an advantage in his battles.
Harry Potter could visit Snape in the hospital. Despite their past differences, Harry might feel a sense of obligation or curiosity. He could be there to finally have an honest conversation with Snape and perhaps gain a better understanding of his actions throughout the years.
Another way Snape could comfort Harry is by standing up for him in certain situations. Maybe when other teachers or students are being unfair to Harry, Snape steps in and defends him. This act of protection can be a great source of comfort for Harry, as it shows that someone is on his side even if they have had a rocky relationship in the past.
Snape might initially be shocked. He's not one to show much emotion openly, but internally he could be very disturbed. He might start investigating what happened to Hermione immediately, using his skills in potions and magic to try and find a cure or at least understand the cause.
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.'