One unique feature is the mash - up of two very different universes. Supernatural's world of demons, angels, and hunters combined with the magical world of Harry Potter where Hermione comes from. It creates a whole new set of possibilities for stories.
Well, 'Forbidden Alliances' is another one. It's a bit darker in tone compared to the others. It shows how Dean and Hermione have to deal with the moral implications of their alliance in a world where the rules of both their original worlds are being constantly tested. The story builds up tension very well and the relationship between Dean and Hermione is complex and engaging.
Well, it's hard to say for sure. The concept of 'porn-like' is quite subjective. Some might consider certain novels with excessive sexual descriptions as such, but it depends on individual perspectives and cultural standards.
In many places, 18+ porn comics are considered illegal. This is because they can have a negative impact on society and violate moral and legal standards.
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.