The central "appeal" in these amateur fictions is the violation of social norms. The narrative focus is rarely on character growth or emotional intimacy and more on the shock value of the incestuous and non-consensual themes.
In the context of storytelling, incestuous relationships can serve as a plot device to examine family dynamics, power struggles, and the complexities of human emotions. However, it's essential to acknowledge that these relationships can also be a sensitive and potentially triggering topic for some individuals.