I think you may be right about that - though it does raise the question, when kinks are involved, are any of them chargeable? You seem to implicitly agree that there would be something chargeable about a bestiality fic (please correct me if I'm wrong), but there's a lot of people who find furryism (furrying? furrification? Is there a noun for this?) disgusting, too*. So where do we put that line? I suspect it's usually around the legal/illegal mark - but that would mean that a few decades ago, we would have been charging for 'homosexual intercourse'.

Thinking about it, it may come down to a consent issue. If a living (or psuedo-living, to cover robots and the like) is the subject of sexual activity, without giving or being able to give consent, that's wrong, and therefore a charge. If both (beg pardon, all) participants are properly consenting - then the mere fact of the relationship isn't a charge. The specifics - such as the characters in question - still can be.

But then we run into the situation that we might be charging something if it's one character doing it, and saying it's okay for the next - purely because one is known to do it, and the other isn't, even if it's otherwise in-character...

hS

*Note that this is not a statement on my feelings, positive, negative, or tangerine-flavoured.