This kind of fanfiction could potentially explore Hermione's curiosity or it might be used to develop a complex plot around her character's exploration of different aspects of sexuality. But it really depends on the specific story and the author's imagination.
The first appearance of lesbian porn stories online is difficult to determine precisely. It likely occurred gradually as the internet grew and different types of content became available, without a clear-cut beginning.
Breast expansion in fanfic often refers to a fictional concept where a character's breasts grow in size, usually in a fantastical or non - realistic way. A breast pump in this context might be a device used in the story related to the breast expansion plot, perhaps for some sort of experimental or medical - like purpose within the fictional world of the fanfic.
They can be used to add a unique and often unexpected element to the story. For instance, the breast expansion might be used to symbolize a character's transformation, and the breast pump could be a plot device that drives the story forward by either causing or resolving the expansion issue.
The main distinction of porn with a story genre from regular porn is the presence of a coherent narrative. Regular porn often jumps straight to the sexual action, while the story genre tries to add some kind of story framework around it. But in the end, both are adult-oriented and feature explicit sexual content.