Common plot elements can include a change in Snape's typical cold - hearted demeanor towards Harry. This could be due to a discovery of a deeper connection between them, perhaps related to Harry's parents. There might also be a plotline where Snape uses his knowledge of magic in a more intimate way to draw Harry closer. Additionally, the fanfictions may explore the reactions of other characters in the 'Harry Potter' world to this new relationship, adding an extra layer of complexity and drama.
Well, often there is a situation where Snape has to protect Harry in a very personal way, which then leads to a shift in their relationship. Also, the fanfictions may play with the idea of Snape's past and how it relates to his new - found feelings for Harry. Maybe Snape starts to see Harry as a way to redeem himself from his own dark past. And there could be a lot of internal conflict within both characters, as this relationship goes against what they've known about each other for so long.
One common plot element could be Snape revealing a hidden, softer side that Harry gradually becomes attracted to. Another might be some sort of magical or emotional bond that forms between them unexpectedly. For example, a shared magical experience that makes Harry see Snape in a new light.