Another theme is the power dynamics. When you combine such powerful groups, there are questions about who is the most powerful and how that power is used. Fanfictions might show Superman and Hulk having a showdown to establish who is stronger, or Iron Man and Cyborg competing in terms of technological prowess.
One interesting 'justice leauge avengers fanfiction' is 'The United Front'. It combines the characters from both universes in a unique way, with an epic battle against a common enemy that neither could face alone. The story delves into how the different personalities interact and form alliances. It's really exciting to see Superman and Captain America strategizing together, and Batman using his detective skills to outwit the villains that are a threat to both teams.
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.
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.