We can examine the views of morality in Buffy the Vampire Slayer with reference to one of the less obviously thoughtful Buffy episodes. In Beer Bad (season 4, episode 5). Buffy is in her first year as a college student, at UC Sunydale. She is very disturbed that a student she spend a night with, Parker Abrams, rejects her afterwards. Some boys in the bar invite her to escape from her sadness by drinking with them. It turns out that the barman, who does not like snotty college kids, added a potion to the beer which turns them all into cavemen.
Before they turn into cavemen, the boys are having one of the conversations that irritate the barman, discussing morality. One of them declares that morality would have been put on a firmer basis under the influence of beer. That would lead to a morality based on what feels good and what feels bad (not the exact wordin g but that undoubtedly is the point).
There is such a morality, since the Nineteenth Century it has been known as Utilitarianism, the position which seeks to maximise the number of states of feeling good. That would be the Utilitarianism of Jeremy Bentham which rates push pin as equal to poetry, that is 'low' pleasure as equal to 'high' pleasure; and not the Utilitarianism of John Stuart Mill who thought there are higher pleasures, so that Socrates unhappy is in a preferable state to a happy pig.
The boys seem to be Benthamites, though their descent into drunken incoherence is not what Bentham thought his philosophy was leading to. The boys progress towards cavemen like prelingualism and rage as a result of drink, could be regarded as a reductio ad absurdum
of Bethamite hedonism, the moral philosophy which seeks to maximise pleasure states. Pursuit of pleasure as a gaol ignores the rational reflective self in theory and leads to its destruction in practice. That may echo arguments of Plato against hedonism, in Gorgias and Philebus. In both dialogues, Plato attacks hedonism by suggesting that it must take the highest state to be that of eating and defecating at the same time, or scratching to relieve a pain. Both arise from seeking pure pleasure but both are repugnant. Pleasure itself can only be acheived in a hedonistic context whichj allows for the rational reflective self.
However, in Buffy, though the morality of hedonism is parodied, the idea that morality is based on feeling good is something difficult to get past. The show is premised on a rejection of moral abstractions. God is out, and so is all religious ethics. There is no absolute standard we can appeal to. The Vampires illustrate this, they defy every moral rule and enjoy the demonic pursuit of cruelty as and end in itself. They represent a logically coherent duty to cruelty as part of nature, which seems reminiscent of de Sade. There is no argument from pure moral reason against the vampires, which is why Buffy has to stake them. She certainly does not have any respect for ideas of moral duty, even if she lives a life of dutgy to her vocation of killing demons.
What makes Buffy different from hedonists turned cavemen? Notions of psychological health come in here, as when Buffy is contrasted with the 'dark' mentally unbalanced slayer Faith. Vampiric duty to kill is resisted with reference to the defence of a rich psychology and a rich way of life which is impoverished by Vampire attacks, and it is a way of life Vampires themselves lack as they are slaves to the lust for pain. The pain they desire is their own as well as that of their victims, they are masochists as well as sadists. One illustration of this is Darla the vampire's wish that Angel, the vampire who gets a soul/conscience should hurt her when he is unwilling to do so. Buffy is also shown to be drawn to the pain and sado-masochism but she also resists it. She resists it from a higher hedonism. Not quite the earnestness of Mill, but an argument for flourishing and richness of life and experience.