Demophon.

    A son of Theseus and Phaedra (or Antiope), Demophon is the subject of a complex and contradictory legend. He and his brother Aca-mas went with the Athenian forces to Troy, where Demophon is said to have joined the embassy to the Trojan court at the outset of the war. At the fall of Troy, Demophon rescued his grandmother, Ae-thra, who had been taken to Troy with Helen, and began making his way homeward. Stopping in Thrace, he fell in love with Phyllis, a Thracian princess, and vowed to marry her upon his promised return within a year. In Athens, Demophon either wrested the throne from a usurper, Menestheus, or gained it after Menestheus’s death. He is also said to have acquired the Palladium, by gift or force, from Diomedes or Odysseus.
    According to some accounts, when Demophon departed from Phyllis she gave him a casket that he was not to open unless he decided not to return to her. When he did not appear by the appointed time, Phyllis cursed him and committed suicide; Demophon, meanwhile, opened the casket and was driven to madness and death by the sight of its contents. In another version, when Demophon did not return to Thrace, Phyllis hanged herself and was transformed into an almond tree. When Demophon finally arrived he embraced the tree, which at his touch burst into blossom. Both of these tales are also told of Demophon’s brother, Acamas.