In a fictional world, I argue, we clearly don't respond to a phenomenon as we would in the real world. We are more likely to see it in terms of the metaphorical or general category that it sketches or stands for. Thus, in the real world we would always be horrified by someone who, while leading an ostensible 'normal' life, was also a habitual killer, who derived enjoyment from his activities. In Dexter, this horror has been suspended. Dexter's murderous noctural activity has become in effect just 'his thing', his particular form of idiosyncratic enjoyment which he cannot relinquish, like book collecting, or motorbikes. Killing is Dexter's jouissance.
By Jouissance is meant a specific form of enjoyment. Not enjoyment as we might speak of enjoying a glass of wine, for example, where we can point to positive qualities which account for our enjoyment - fruityness, dryness and so on. Jouissance is something more compulsive, stupid and unaccountable. The idea is that in fact all of us have these idiotic knots of enjoyment, perverse and idiosyncratic, that we are not finally able to share with others. As such these knots bar our full inclusion within the human community. In extreme cases, they can eclipse the rest of our life, as Zizek puts it:
Someone can be happily married, with a good job and many friends, fully satisfied with his life, and yet absolutely hooked on some specific formation ("sinthome") of jouissance, ready to put everything at risk rather than renounce that (drugs, tobacco, drink..) [..] It is only in this "sinthome" that the subject encounters the density of his being - when he is deprived of it, his universe is empty.Jouissance in this sense is always anti-social, and there is always a tension between it and the laws of the symbolic community, the norms and rules of social enjoyment. In so far as these last consitute the 'human community' as we experience it, none of us are entirely human.
Ingeniously, Dexter turns the extremely pathological - the serial killer - into a figure for the human as such.We are all pathological subjects trying to become human, perversely clinging on to our jouissance. AS such, we are on DEexter's side.