I'm not aware of any such fanfiction that is entirely appropriate for all audiences as the concept of 'spanking' in this context can be inappropriate and not in line with general family - friendly content. It's better to focus on positive and respectful portrayals of characters in fanfiction.
A theme about Snape's role in the wizarding war from a different perspective could also be interesting. Maybe a story where he has to work undercover with other characters to gather intelligence against Voldemort. This would show his intelligence, cunning, and loyalty in a more appropriate and engaging way compared to the inappropriate 'spanking' theme.
Rather than focusing on this specific and somewhat unusual type of fanfiction, you might want to explore more general Severus Snape fanfictions. There are many great ones that delve into his character, his relationships in the wizarding world, and his backstory. These can be found by simply searching for 'Severus Snape fanfiction' on popular platforms, which will give you a wider range of engaging stories to choose from.
In these fanfictions, Snape often becomes more self - reflective. He starts to realize the full extent of his actions and how they've affected others. For example, he might come to see how his treatment of Harry was unfair. He also becomes more open about his emotions, which was something he always hid before.
Personally, it's a rather strange concept. Fanfiction often takes characters in unexpected directions, but this seems a bit out of the ordinary. However, everyone has different tastes in fan - created content, and as long as it's within the boundaries of legality and respect, it has its place in the fanfiction community.
In some fanfictions, Severus Snape's character develops by becoming more open - minded towards Muggles. He might start off with his typical wizarding - world prejudices, but through various interactions, he begins to see Muggles in a new light. For example, he could meet a Muggle scientist whose thirst for knowledge reminds him of his own love for potions, and this changes his view.
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.
His complex personality makes him a great subject for fanfiction. He's often seen as a brooding and mysterious figure in the original books. This gives writers a lot of room to explore his deeper emotions and motives. For example, his love for Lily is a very rich area to write about.
In this fanfiction, Severus Snape's character is likely to be explored in depth. His 'heart' could refer to his hidden emotions, his capacity for love or loyalty that was often masked in the original series. It might show his softer side that was rarely seen, perhaps in his relationships with other characters like Harry or Lily.
Snape's character could become more complex. He might start to incorporate some of Merlin's wisdom into his own actions. For example, Merlin was known for his ability to see the good in people, and Snape could start to do the same. Instead of just being bitter and resentful towards Harry, he could start to see Harry as a potential ally in a greater fight, much like Merlin saw the potential in the young knights of Camelot.