Given the dominance of pairings in fan fiction, (…) the opposition between romance and sex can look like a sliding scale of visibility between G-rated stories, in which romance itself is only implied, and NC-17 stories, in which sex is explicitly represented. This emphasis on the visibility of sexual content through the use of the ratings system reveals the extent to which this assessment is drawn from the generic conventions of pornography. However, very explicit stories may also be very romantic, and the most popular romance stories may focus explicitly on sex. The genres are not poles at either end of the scale but axes between which every story can be plotted as more or less romance and more or less porn. Porn may be a slight or dominant element of a fluffy romance, and romantic completion can be used to ground PWPs as a rationale for the sex. Even this imaginary graph is a gross simplification, because porn and romance are not so separable in fan fiction and because they are not the only terms by which fan fiction is classified. Nevertheless, I would argue that while much fan fiction is explicitly romance and/or porn, all fan fiction is implicitly both.
Driscoll, C. (2006). One True Pairing: The Romance of Pornography and the Pornography of Romance. Fan Fiction and Fan Communities in the Age of the Internet
Driscoll uses the example of fanfiction to re-evaluate the relationship between the genres of pornography and romance. For her, fanfiction is at least implicitly both porn and romance. She finds two types of sex in fanfiction. “Plot sex” is used to develop characters, further the plot and provide closure to a romance narrative. “Porn sex”, on the other hand, is written for its own sake, with the focus physical sex acts, like pornography. Importantly, porn sex in fanfiction – even in PWP stories – must retain an element of plot or characterisation in order to remain fanfiction. Even if such characterisation is only accessible to those who know the source material well, it has to be there for the work to still be fanfiction.