An anguished Lavinia appears inside her father's study. A portrait of Ezra in a judge's robe hangs above the fireplace. His face strikingly resembles Adam Brant's and bears the same mask-like quality of his wife and daughter's. Lavinia protectively lays her hand one of Ezra's.
Christine enters affecting a scornful indignation and questions why Lavinia has summoned her. Lavinia reveals that she followed her to New York and discovered her kissing Brant in a rented room. Christine starts momentarily and then regains her defiant coolness. She tells her daughter that she has hated Ezra since the beginning of their marriage. Lavinia was born of her disgust. Christine tried to love her but always felt that she was of Ezra's flesh. She loves Orin precisely because he has always seemed hers alone. If Orin had remained with her, she would have never taken up with Brant.
Lavinia taunts that Brant only seeks revenge and does not love her. Christine already knows Brant's secret past and asks what Lavinia intends to do. To her surprise, Lavinia wants to keep Christine's secret for Ezra's sake though she has written Ezra and Orin of Brant to arouse their suspicions. Christine must promise only to never see Brant again.
Laughingly Christine accuses her daughter of wanting Brant herself. Lavinia has always schemed to steal her place; she has always tried to become the wife of her father and mother of her brother. When Christine threatens to refuse, Lavinia reminds her that Ezra would ruin Brant and never divorce her. As she aged, Christine would become an anchor around Brant's neck.
After a sinister pause, Christine agrees to Lavinia's terms. A suspicious Lavinia threatens that she will be watching her. She leaves to get the latest news on Ezra's return. Brant awaits Christine outside. Alone, Christine pauses in tense, sinister calculation, decisively takes a slip of paper on the table, and writes two words on it. "You can thank Vinnie, Ezra!" she cries at the portrait.
Brant enters and bristles tensely at Ezra's portrait and then unconsciously assumes its position at the desk. Asking if Orin resembles his father, he notes that it would be "damned queer" if Christine fell in love with him because he recalls Ezra. He remembers hating her for being Ezra's when they first met and pledging to take her from him in revenge.
In Mourning Becomes Electra you write: "Oedipus was the Theban king who unwittingly killed his father and MURDERED his mother." [Emphasis mine].
It should read: "Oedipus...MARRIED his mother!"
(Oedipus' mother Jocasta did commit suicide after learning her lover was her son. Oedipus however did NOT "murder" her.)