Erotic fantasies are fascinating psychic contents which are at the origin of normal sexuality, but also abnormal sexuality. Our hypothesis is that their structures (logical, temporal, in contents) explain their motivating force in acting out.
I think this is a fascinating topic. For sexual fantasies involving paraphilic themes, there is clearly a distinction between those involving targets (e.g., pedophilia, fetishism) and those involving activities (e.g., masochism, voyeurism).
There are also structures within paraphilias, e.g., we did a small clinical study years ago that showed the fantasies of self-identified sexual masochists were organized around different themes, particularly a theme around submission and another theme around physical suffering/pain.
Freund, K., Seto, M. C., & Kuban, M. (1995). Masochism: A multiple case study. Sexuologie, 4, 313-324.