Orestes is the tragic hero of The Libation Bearers and Eumenides, the final play in the Oresteia cycle. Orestes feels a deep loyalty to his family. He also bears the burden of being responsible for the House of Atreus's continued survival. As a son of a royal family, he has a civic responsibility to the city of Argos, too. Throughout the play Orestes wrestles with his obligations to the gods, his parents, his sister, and himself. His internal struggle and ultimate desire to do the right thing drives the plot forward.
Electra grieves her father's death and feels neglected by her family. Although technically a free woman and a daughter of the royal family of Argos, she identifies closely with the enslaved Trojan women who work in the royal palace. Her prospects are limited under the rule of Aegisthus, and she can't speak freely. Her only close relationship is with her brother, Orestes, the single family member she can trust. Throughout the play Electra appears emotional, confused, and pessimistic about her own future in the family. Her fate is not revealed at the end of the play.
Clytaemnestra wields authority with intelligence and confidence. As head of the royal family, she values keeping up the appearances of a respectable family unit, such as extending hospitality to guests. She can be impulsive and quick to act, especially when she feels her life or power is in danger. Although she's treated as a villain by her son, Orestes, and the Chorus, she does appear to have a moral code and a sense of maternal obligation—she murdered her husband, the king Agamemnon, to avenge her sacrificed daughter, Iphigeneia.
Aegisthus is a conceited ruler with high regard for his own strength and intelligence. Despite his superior status as Argos's (illegitimate) king, he is not as influential or skilled at planning as his lover, Clytaemnestra.
The women in the chorus are wise, patient, and crafty. They despise Clytaemnestra's rule and support Electra and Orestes wholeheartedly. They are forced to keep silent about their true feelings in the palace but speak freely at Agamemnon's grave. By influencing the palace residents, they're able to silently aid Orestes in his quest for revenge.