One reason is the complex relationship between Snape and Harry in the original Harry Potter series. Writers are intrigued by this relationship and use the idea of Snape pinning something on Harry as a way to explore it further. It could be a symbol of protection, a sign of a hidden connection, or a device for plot development.
One possible reason could be that Snape suspects Harry of something. Maybe he thinks Harry is involved in some sort of mischief or is in possession of something he shouldn't have. Snape has always been a bit of a mystery and is often distrustful of Harry, so this action might be his way of getting to the bottom of things.
One great Snape pins Harry fanfiction could be 'The Unexpected Bond'. It explores the complex relationship between Snape and Harry in a unique way, with Snape using the pins as a sort of symbolic connection to Harry. Another one might be 'Pins of Protection' where Snape gives Harry pins that have magical properties to help him in his battles against the Dark Arts.
Harry might struggle and try to break free. He is a brave character and doesn't like being restrained, so he would likely use his physical strength and magic skills, if possible, to get out of Snape's hold.
One possible reason could be that Snape is trying to intimidate Harry. He has always had a rather tense relationship with Harry in the original story, and this could be an extreme form of showing his authority. Maybe he suspects Harry of something, like being involved in some mischief or having knowledge about a certain Dark Arts item or activity.
Another reaction could be fear. Despite his bravado at times, Snape can be an intimidating figure. If Harry is caught off - guard, he might feel a moment of real fear. His heart could start racing and he might struggle against Snape's hold, but be too afraid to say anything at first.
In some fanfictions, it initially worsens their relationship. Harry might feel violated or extremely angry that Draco would use physical force on him. This could lead to a period of intense hatred and more frequent clashes. However, as the story progresses, this event could also be the catalyst for them to eventually make amends and develop a more complex relationship.
One interesting scenario could be in a Quidditch match gone wrong. Maybe Draco, in a fit of over - competitiveness, pins Harry against the side of the stadium during a mid - air scuffle. It could be a moment of intense rivalry and unexpected physical contact that changes their dynamic.
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.
In some fanfictions, Snape might use his advanced knowledge of potions to brew a special healing elixir for Harry. He could also use his magic skills, like a complex spell specifically designed to mend Harry's wounds, whether they are physical or emotional.