The plot of The Last Centaur was formulated as soon as I devised the prophecy delivered by the Pythia to Nessus in Becoming Jason, the prophecy that quoted in the prologue of the short story. The story describes the fatal final confrontation of two pivotal characters in Becoming Jason - Heracles and Nessus. The story is based seventeen and a half years after their final encounter in Becoming Jason, in summer 1229 BC. For more details, see the chronology under the cross-reference acronym TLC (The Last Centaur). Both Heracles and Nessus are quite old, both for their own reasons frustrated with their lives.

Most of the myths that form the basis of this short story are attested in historical sources:

• Heracles' willing servitude to Eurystheus in exchange for the promise of immortality.
• The encounter of Heracles with the centaurs, including Nessus, on Mount Pholoë.
• Eurytion's attempt to rape the daughter of Dexamenus and his subsequent death at the hands of Heracles.
• Heracles' marriage to Deianeira and self-imposed exile from Calydon.
• The exile of Tydeus from Calydon.
• Nessus' attempted rape of Deianeira, death at the hands of Heracles and final gift to Deianeira.

The key aspect I have added to the extant myths is the prophecy Nessus receives during Becoming Jason, a prophecy which Nessus chooses to embrace rather than seeking to avoid. The deaths of most of the centaurs are also not attested in myth, but it suited my purpose for Nessus to be the final centaur. It is not implausible to believe that they have been slaughtered by the humans, for whom they hold a mutual antipathy. And after the Centauromachy most of the centaurs play no part in subsequent myths. Another divergence from received myth is that Nessus has usually chosen the job as the ferryman on the River Evenus. But a career serving and aiding humans is not consistent with the character of Nessus or the centaurs and it suited my purposes better for him to assume the role by force. Another invention is Heracles' apprehension about water. But it is a traditional trait that heroes have a fatal weakness and aquaphobia seems a fitting failing for such a physically strong character. Deianeira's feelings towards Heracles following their exile and the attempted rape by Nessus are also not attested in any traditional myth. I will allow you to draw your own conclusions about whether or not Deianeira perceives the truth behind the gift from Nessus. In my opinion, the naïvete of the words of Dieaneira in Sophocles Women of Trachis certainly seems hard to believe.

The language and events in the short story are deliberately harsh and brutal. Even though I never shrink from a vivid depiction of conflict and death (and nor did the ancient tragedians and epic poets), the language is more extreme than the style used in Becoming Jason. But this was a conscious decision to reflect the character of Nessus and the centaurs. Moreover the depiction of the effect of the hydra's venom produces a contrapuntal juxtaposition beside Heracles' renown as a civilising hero.

This is one of the themes of the story, picked up from Becoming Jason: civilisation versus barbarism. Heracles is, notionally, the hero of the civilised world. But it is significant that this hero's main weapons are the arrows steeped in the venom of the Lernaean hydra which deal such death. Nessus, like his brothers, accept their inbred barbarity and consequently the actions and tone of Nessus are unashamedly savage befitting a creature only partly human and a child of rape.

The theme of fate and prophecy is the central theme of the short story and one that is also a key theme of Becoming Jason and indeed the whole Jason and Medea saga. Both Nessus and Heracles have their own approach to the prophecies they have received. Those attitudes are also investigated in Becoming Jason, as indeed are the attitudes to fate of Oedipus, Jason, Aegeus, Cheiron and Peleus. Understandably, different characters receive differently prophecies about their future, and their reactions are a reflection of their differing personalities. Although many of us cannot admit to having received prophecies in the same way these Greek heroes did, nonetheless we all approach opportunity and misfortune differently, accepting or moulding our lives depending upon our characters.

Another significant theme of the short story is the role of women. I did not want to make Deianeira a weak character and chose to make her disdainful at the weakness of Heracles in choosing exile rather than facing his misdeeds. By the time of this short story, the events of the Jason and Medea saga will have run their course, and so I have made Deianeira demonstrate some envy of Medea's strength of character, her eagerness to take control of her life from the men who would control her.

As in Becoming Jason I have sought to understate the fantastical elements of Greek myth, but not to the same extent as the historian Diodorus Siculus. Consequently, the poisonous blood of the hydra seems like a corrosive acid that eats through flesh (omophagia) and bone, made potent by the heat of the sun.