From the scene change to the exit of Cilissa. (Lines 653-782):
We now have a scene change. We are no longer at the tomb of Agamemnon, but before the doors of Clytaemestra's palace. Orestes, accompanied by Pylades, knocks on the palace doors. He says to a servant that he brings important news for the masters of the house. Clytaemestra comes out to greet them; she offers hospitality and asks to hear the news. The disguised Orestes tells her that on his way to Argos, he was told to inform the rulers of Argos that Orestes is dead. Clytaemestra receives the news with apparent sorrow. She assures the disguised Orestes that the hospitality offered to him will not suffer, despite the fact that he is the bringer of terrible news, and she tells a servant to make sure that the two travelers receive every benefit of hospitality. She will talk to Aegisthus and some trusted friends about this sudden turn of events. Everyone exits except for the Chorus.
The Chorus prays for Orestes' success. Cilissa, an old nurse, enters with tears in her eyes, and the Chorus asks her why she is crying. Cilissa says that Clytaemestra seems sad, but Cilissa thinks that the queen hides inner happiness at the news; Orestes can no longer endanger the queen and Aegisthus. Clytaemestra sent Cilissa to fetch Aegisthus, so that he might hear the news, too. Cilissa is grieving for Orestes. She raised him as if the boy were her own son; as was not uncommon in rich Greek households, Orestes' parents had less to do with his upbringing than his nurse. She raised him from infancy, and now she has lost him. She must bring the news to Aegisthus, whom she clearly hates.
The Chorus asks Cilissa if Clytaemestra told Aegisthus to return home armed and with bodyguards. Cilissa says yes; the Chorus tells her to instruct Aegisthus otherwise. He should return home alone, unarmed. They hint that Orestes may still be alive. Cilissa does not understand, but she agrees to do as asked. She is not sure what is going on, but she will trust the slave women and hope for the best.
Orestes may be acting under the orders of Apollo, but there is much in his plan that is savage and sneaky. Deception and ensnarement is a theme of the trilogy. He hopes to ambush his mother and Aegisthus in a manner as underhanded as the ambush in which Agamemnon was murdered. Onstage at the same time, we see mother and son both in disguise. Cilissa says that Clytaemestra puts on a face of sorrow to hide a truer, inner face of happiness. Orestes hides his face under the costume of a foreign traveler; he even affects an accent to complete the disguise. Although Orestes insists on the justice of his actions, putting disguised mother and disguised son onstage at the same time suggests that there are many parallels between murdering Agamemnon and murdering Clytaemestra and Aegisthus. In both cases, deception is a prelude to the killing. In both cases, the killer feels that he or she is serving justice. And in both cases, the murder also amounts to usurpation of the throne of Argos.
Although the nurse is skeptical of Clytaemestra's sorrow, Aeschlyus' characterization of the queen is round enough for us to think that at least some part of Clytaemestra's sorrow is real. Certainly, she is not completely honest. She implies to the stranger (the disguised Orestes) that the prince was a source of happiness; strange words, coming from the woman who exiled him. Cilissa is right about one thing: some part of the queen feels relief. Orestes is the legitimate heir to the throne, and his exile did not end the threat of his returning to avenge his father. Clytaemestra's dreams increased her fears of her son's return. The mixed emotions Clytaemestra feels is yet another manifestation of the hate-in-love theme. She feels both sorrow and happiness at news of her son's death.
The old nurse's sorrow is a sharp contrast to Clytaemestra's reaction. Although we can believe that Clytaemestra is sad to hear that Orestes has died, note that we can find no speech or stage directions that indicate tears from Clytaemestra. Aeschylus imbues the queen with grandness and dignity throughout both Agamemnon and The Libation Bearers. She is composed and unshakeable, no matter what happens. But here that self-control comes off as overly composed, too inhuman. Clytaemestra's measured and careful reaction to her son's death seems all the more cold when juxtaposed with Cilissa's emotional and sincere reaction; the slave weeps for a boy who was not even of her blood, calling his death the greatest pain she has had to bear. This contrast between queen and slave nurse reveals Clytaemestra's determination and composure while also showing her unlikable traits. As is often the case for the tragic figures of Greek literature, Clytaemestra's strengths are inextricable from her faults.
The Cilissa/Clytaemestra juxtaposition may also be social commentary on the child-rearing practices of the Greek nobility, in particular the nobility of Aeschylus' own city of Athens. Frequently in Athens, many of the responsibilities of childrearing were left to slaves. Although the Curse in the Oresteia should not be reduced to a story about what goes wrong when Mommy pays no attention to Baby, Aeschylus' use of the Cilissa character is too carefully placed and prominent for it to be accidental. The most specific criticisms can also be the most general: in revealing Clytaemestra's faults as a mother and a human being, Aeschylus may be subtly criticizing a certain method of parenting.
Whatever their justification for slaying Agamemnon, Clytaemestra and Aegisthus clearly have not made themselves loved. The success of Orestes' plan rests on the dissatisfaction of slaves in the house. The Chorus does not only comment on the action: here, the Chorus is a co-conspirator. The nurse Cilissa hates Aegisthus and wastes little love on Clytaemestra. Tyranny was a hot political issue for Athenians, who had some experience with tyranny: the original definition of "tyrant" was a strong noble, often with good intentions, who ruled as dictator. Tyrants seized and maintained power by force. Tyrants may have been effective rulers at times, but their abuse of the system and flaunting of the rules made a city under tyranny dangerously subject to the whims of one man. A history of these abuses led to the overwhelmingly negative definition of the word that eventually evolved, the definition still in use today. Agamemnon may have had many shortcomings as a ruler, but his wife has done little since his death that would justify his murder. All of the servants of the house despise her and her lover.