The story goes that Pirithous and Theseus made a pact that they should both marry daughters of Zeus, because they were demigods and as such deserving of marriage to women of divine lineage. Leaving aside the fact that a daughter of Zeus would also be Pirithous' half-sister and the marriage slightly incestuous, a demigod deciding he deserves some kind of honor or another for himself is never really a good idea. Hubris is never, ever, ever a recipe for success for any demigod or mortal. The gods just do not put up with it.
|Hades making off with Persephone|
Where Pirithous really went wrong then, was in his play for Persephone, a goddess in her own right as well as the consort of Hades, Zeus' own brother. Theseus merely went after a demigod, and while I won't say he didn't suffer for his pact in that regard, he certainly did not suffer for it to the same extent that Pirithous did. It's said, however, that Pirithous went after Persephone because Zeus SENT him, for the sole purpose of seeing him punished.
When Jove saw that they had such audacity as to expose themselves to danger [kidnapping Helen], he bade them in a dream both go and ask Pluto on Pirithous’ part for Proserpine in marriage (Hyginus, Fabulae, 79).So it wasn't even the pact to marry daughters of Zeus that provoked the gods, so much as how they went about kidnapping Helen herself. Now, Hyginus also says that Heracles pulls them both back out of the underworld, but Apollodorus says otherwise in The Libraries:
And being come near to the gates of Hades he found Theseus and Pirithous, him who wooed Persephone in wedlock and was therefore bound fast. And when they beheld Hercules, they stretched out their hands as if they should be raised from the dead by his might. And Theseus, indeed, he took by the hand and raised up, but when he would have brought up Pirithous, the earth quaked and he let go.Pirithous being Pirithous, I'm not sure it would surprise me all that much if he got it into his own head that Persephone wanted him, and it would be a good idea to go steal her, for which he would then deserve the punishment of being trapped in Hades for eternity. But if he only went after Persephone because of Zeus? Well, that changes things. Why shouldn't Pirithous follow the direction of the King of the Gods, with all hope of success in his venture? With Zeus' blessing, how could he fail?
It makes you wonder. How many sins did the gods first impose upon their heroes, just for the excuse of punishing them? And was Pirithous a victim of his own Hubris, or the gods' desire to remind the world about just WHO exactly was boss?