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.
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.
Harry might react with defiance. He has always been a brave character, so he could look Snape straight in the eye and not show any fear, even though he is in a vulnerable position.
Well, it could be a story about a moment of intense emotion. Maybe Saskue is angry at Sakura for some reason and pins her to the wall in a fit of rage. But then it might turn into a moment of realization for both of them, leading to a deeper understanding of their relationship.
The main characters are clearly Saskue and Sakura. Saskue is likely to be a complex character in this fanfiction, with his own motives and emotions that lead him to pin Sakura to the wall. Sakura, on the other hand, is probably the recipient of Saskue's actions and will have her own reactions and responses to the situation.
It could be about a very dark and twisted situation where 'pain' is personified and is physically restraining or harming'sakura' in some way. Maybe it's a psychological horror story where sakura is a victim of some malevolent force represented by 'pain'.