Lavinia is based upon the character of Electra in the Oresteia. Like Electra, she has an attachment to her father that overwhelms her. It is from Electra that the Freudian psychological term Electra complex comes. Awkward and somewhat military in her manner, Lavinia takes after her father more than her mother. She cannot see attaching herself to another man, such as her neighbor and friend Captain Peter Niles. She simply can't imagine loving anyone except Ezra, whom she views as perfect. She is prepared to challenge anyone who hurts him. After his death her primary concern is for his reputation, even if defending it means destroying the reputation of the rest of the family. In the early acts, Lavinia comes across as guileless and incapable of manipulating people. In the end it becomes clear that she is a master manipulator who has gotten Orin to do her bidding. Moreover, once her mother and father are dead, she comes into her own as a sexual being.
Christine Mannon is based on the character Clytemnestra in the Oresteia, who murders her husband, Agamemnon. However, Clytemnestra arguably had good reason to murder Agamemnon. He had sacrificed their daughter, Iphigenia. Christine, meanwhile, has no visible reason to want Ezra dead other than wanting to keep all his money and be with her lover, Captain Adam Brant. She has a weirdly close relationship with her son, Orin. She encourages his odd attachment to her and uses it to her advantage. She has been less successful at making her daughter into someone she can manipulate. This is because she was apparently cold to Lavinia all along. Still, she does manipulate Adam Brant into helping her kill her husband. But in the end she is terrified of what she has done and the consequences.
Orin Mannon, who parallels Orestes in the Oresteia, has seen the atrocities of the Civil War, and he cannot stop seeing them. He seems to suffer from post-traumatic stress disorder as a result, when soldiers experience traumatic flashbacks and anxiety. His father sent him to war to make a man of him, and he wanted to make his father proud. However, he has returned obsessed with death and with the idea that killing is just a matter of course. Injured in the war, Orin was eager to return to his mother, Christine, with whom he shares an extremely close relationship. When he returns home, everything has changed. His father is dead, and though Christine says she had nothing to do with it, Orin suspects she did. His sense of family honor is strong enough to want to cover it up. Still, such a betrayal must be avenged.
Captain Adam Brant
Captain Adam Brant, who was born out of wedlock, is the son of Ezra Mannon's brother, David, and a lowborn nurse named Marie Brantôme. Adam Brant is similar to Aegisthus in the Oresteia. His father was rejected by the Mannon family for his father's choice of a wife, and Brant grew up in a situation of poverty and abuse. After Brant's father died, his mother appealed to Ezra Mannon for help and got nothing. Now, having risen above it to become a successful sea captain, Brant plans to avenge himself on the Mannon family. He pretends to court Lavinia Mannon while actually romantically pursuing Lavinia's mother, Ezra Mannon's wife. Whether he actually loves Christine or is simply bent on revenge is never fully clear. However, he ends up dying for her.
Ezra Mannon was born wealthy, but he made more money. A respected member of the community, he was a judge and politician before serving in the military. His service was inevitable despite his wealth, because he attended West Point and wanted to serve. He also wanted his son, Orin, to serve so that he could become a man and make him proud. He has traveled a great deal and, now that he's older, regrets that he isn't as close to his wife as he should be. He does, however, have a soft spot for his daughter, Lavinia, who is his favorite child. Ezra suffers from a heart condition, which makes it hard for him to hear the news that his wife is cheating on him. However, his condition doesn't kill him. His wife does.
Hazel and Peter Niles basically function as a unit in the play. One is seldom seen without the other, though Peter is based upon a character in the Oresteia—Pylades, friend of Orestes—while Hazel is not. Both are old friends of the Mannon siblings, and both want to marry them. They don't serve a strong purpose in the play, but they sometimes build tension. Peter is used to show that Lavinia has no real interest in men other than her father. Peter is a gentle soul who is deeply affected by what he saw in the war. However, he is fortunate not to have experienced as much as Orin Mannon did. Peter seems too normal to keep pursuing Lavinia for long.
Hazel and Peter are siblings and usually appear together. While Peter is based upon a character in the Oresteia, Hazel is not. Both are old friends with romantic aspirations toward the Mannon siblings. They don't serve a strong purpose in the play, though Christine Mannon tries to use Hazel as a weapon against Lavinia Mannon. Hazel is a mild-mannered character who seems to want to go along with Christine. However, both Niles siblings are ultimately too sensible to be involved with the Mannons.