Prometheus The Fire-Bringer
Only one fragment survives from this play. Despite the paucity of direct evidence, Prometheus' foreshadowing of future events in the trilogy's first play suggests that the final play concerned itself with Prometheus' knowledge of a secret that could potentially lead to Zeus' downfall, and how the revelation of this secret leads to reconciliation between the Titan and Olympian. The secret is this: the sea nymph Thetis, whom Zeus wants to take as a lover, is fated to bear a child greater than its father. Lying with her, then, would result in Zeus' being overthrown just as he had overthrown his father, Cronus. During the course of the drama, Prometheus decides to warn Zeus about Thetis. Rather than lie with her, Zeus marries her off to the mortal Peleus, King of Aegina. The product of this union will indeed be a son greater than the father, namely Achilles, Greek hero of the Trojan War. Finally, Athenaeus (a grammarian of the 2nd and 3rd centuries AD) wrote in Book 15.16 of his Deipnosophists the following regarding a contemporary Athenian festival dedicated to Prometheus: "Aeschylus clearly states in the Unbound that in honor of Prometheus we place a garland on the head as recompense of his bondage." Some scholars have taken this to mean that in the Unbound, Prometheus prophesies that eventually (in the Fire-Bringer), Zeus would reconcile with him, and establish some sort of festival in his honor. Given the title of the play, and taking a cue from the aetiology for the Athenian Areopagus provided by Aeschylus' Eumenides, it has been suggested that the drama concludes with Zeus' foundation of the yearly torch race that took place in Athens to honor Prometheus.
A minority of scholars believe that Prometheus the Fire-Bringer is actually the first play in the trilogy. One reason is that Prometheus Bound begins in medias res; some have observed that after the reconstructing the Bound and Unbound as the first and second play, there simply isn't enough mythic material left for a third-position Fire-Bringer. According to his theory, Prometheus the Fire-Bringer would dramatize the Titan's theft of fire as described in the Theogony.
Read more about this topic: Prometheia