You accused me of employing one of the most basic (and in my opinion the most dire) logical fallacies---when I most certainly didn't, either denotatively or connotatively. Of course I'm going to reply. It's personally offensive to me as well as false

I asked "what is the term for X?" and you (or, strictly, another commenter, whose comment you endorsed) replied "Fictional!". You know perfectly well that that was nothing but a wisecrack reply. To state the freaking obvious, the meaning of "fictional" is "not real" and is thus much, much, broader than what I was looking for. For one thing, the term includes heroes as well as villains! There are plenty, plenty of fictional characters who do not meet the description I provided (a description which was not even intended to be taken literally, but merely as a pointer to the closest empirical cluster -- as is the standard convention in ordinary human conversation, which this was intended as an instance of, because [newsflash!] the original comment was an offhand remark!)

And no, I did not in that instance mean to accuse you of a fallacy. The "non sequitur fallacy" is only one of two commonly used senses of the term "non sequitur". The other is a remark which is inappropriate in the context. For example, if I say "The moon is made of green cheese", and you, instead of saying "What?! No it isn't", say instead, "I wonder whether my uncle Harry would like to buy a new car", that could be described as a "non sequitur" -- an utterance which isn't an appropriate way to follow the previous one. That is what I meant to accuse you of. Maybe it was an ill-considered accusation, maybe there is a better, more precise term for a wisecrack remark that superficially appears to answer the question but actually doesn't and is merely a rhetorical way to dismiss the question and cause the asker to lose status....but I didn't think of it in time -- I was too busy acting quickly to fend off what I expected would be an onslaught of upvotes for you (or, rather, your confederate), maybe even accompanied by downvotes for me.

I'm not a psychiatrist and The Joker isn't real ....the Joker, being the creation of cartoon writers not remotely trying to be realistic

Anybody trying to be charitable would realize, would assume, that the fictional character was cited only for the sake of convenience. Now, evidently we have a substantive disagreement about whether the traits in question are actually possessed by any real humans, but the reference was made before that disagreement was revealed. Had I known your and JoshuaZ's beliefs about the matter, I never would have used a fictional example.

JoshuaZ gave you substance too, including a reference to resources that explain what sociopathy is actually like.

I don't actually care, in this context, about what sociopathy is "actually like" if the word refers to a phenomenon other than the one I intended to refer to. If you and JoshuaZ believe the phenomenon I had in mind doesn't exist, that would have been enough of a nontrivial point to make without going into the tangential subject of the separate, unrelated phenomenon that (apparently) receives the label in standard clinical discourse.

I will simply note my disagreement and move on.

And I will note that you have chosen to do so in a manner that I evaluate as a rather significant interpersonal defection

Well, I'm sorry to hear that -- but I felt under attack from your comments, which seemed rhetorically excessive and out of proportion to my own. I was merely seeking to "tap out" without conceding anything.