Following the fall of Troy and the rescue of his grandmother Aethra, Demophon is said to have landed in Thrace on his return journey, where he met and married Phyllis, the daughter of the king.

As king, he gave refuge and land to the Heracleidae in Athens, fought Diomedes and wrested the Palladium from him, presided over the creation of the court of the Ephetae, and hosted Orestes during his madness.

[3] After his father journeyed to the underworld with his friend, Pirithous, he lost the throne of Athens upon his return to Menestheus, supposedly in 1205 B.C.

During the Fall of Troy, after making their intentions known to Agamemnon, Demophon and Acamas freed their grandmother Aethra, Helen's handmaid who had been captured by the Dioscuri while Theseus was in the underworld years before, and brought her home.

According to some sources, Demophon, stopping in Thrace on his return journey from the Trojan War, married Phyllis, daughter of a Thracian king (possibly Sithon).

On the day after the wedding, however, he decided to complete his voyage and sail to Athens, promising to return to Thrace and take Phyllis with him as soon as possible.

[6] Others, however, say that he did return to Thrace, but Phyllis was already dead by the time; when he embraced the lifeless almond tree into which she was said to have transformed after death, it started to blossom.

[10][11][12] Not all sources, however, accepted the tradition of Demophon's death in Cyprus, stating he was one of the few heroes fortunate enough to return home safely.

In Euripides' play Heracleidae, and in other sources, Demophon became king of Athens, having succeeded Menestheus after the latter's death (said to have occurred in 1183 B.C.).

King Demophon marched out against the invaders, and, after the Athenians slew numerous Argives, was successful enough to wrest the Palladium from Diomedes, who had taken it from Troy.

[14][15] Later, Orestes, seeking asylum after avenging his father, Agamemnon, by murdering his mother and her lover, arrived in Athens during Demophon's reign.

[10] As Orestes arrived during the celebration of the Anthesteria, precautions were taken by the king that he would not pollute the sacred rights, resulting in the second day of the festival, called Choes.