In Greek mythology, Ismene was a Theban princess, daughter of Oedipus and (in most accounts) Jocasta, and sister of Antigone, Eteocles, and Polynices. In Sophocles she is the cautious foil to Antigone: she refuses to help bury Polynices against Creon's edict, then later offers to share her sister's punishment. Earlier poetry preserves a different tradition in which Tydeus kills her.
Adapted from Wikipedia, "Ismene" · CC BY-SA 4.0
I.Family
Traditionally Ismene is the daughter of Oedipus and Jocasta (or Epicaste), king and queen of Thebes, with full siblings Antigone, Polynices, and Eteocles. In the lost Oedipodea, Pausanias reports, the children of Oedipus were mothered by Euryganeia rather than by the incestuous queen — a reading some scholars connect with Homer's claim that the gods revealed the incest "straightaway."
Some modern scholars suggest Ismene was originally a separate Theban heroine later folded into Oedipus's family by the fifth-century tragedians. This atlas node is the sister of Antigone in the Theban house, not an unrelated namesake.
II.Early traditions
The seventh-century poet Mimnermus has Tydeus, one of the Seven, murder Ismene while she is with her lover Theoclymenus (or Periclymenus on a Corinthian amphora), after Athena reveals their whereabouts. That tradition cannot be reconciled with Aeschylus and Sophocles, in which she survives the war. Ion of Chios has Laodamas burn Ismene and Antigone alive in Hera's temple.
III.In Greek tragedy
Aeschylus first identifies her clearly as Oedipus and Jocasta's daughter; at the close of Seven Against Thebes she and Antigone sing a funeral dirge, then escort the brothers' bodies separately. In Sophocles's Oedipus at Colonus she brings news of Thebes, performs purification rites for her blind father, and is seized by Creon before Theseus frees her.
In Antigone she refuses to join the illegal burial, urging secrecy if Antigone proceeds; after Antigone is caught she claims equal guilt and asks to die with her, but Antigone refuses to let her share a martyrdom she did not choose. The pairing of defiant Antigone and law-abiding Ismene became a lasting emblem of conflicting goods under tyranny.