How we cite our quotes: (Volume.Book.Chapter.Line)
Quote #1
He might be ill, and it might suit you to know it, but no contact with him, for this, could ever be straight enough. (1.1.1.4)
Kate Croy has spent a lifetime dealing with the deception of her awful father. The man might be ill or dying, but she can never be sure because her father seems to have built their entire relationship on lies, even when the lies don't matter. He's a super pathological liar.
Quote #2
"Ah, I shan't perhaps come up to your idea. It's only to deceive Susan Shepherd." (1.5.2.24)
When Milly asks Kate to do something bad with her, Kate expects something scandalous. But Milly just wants Kate to help her deceive Susan by hiding the fact that she visited a doctor. This might not be a big deal for Kate, but for Milly this lie is a sign of independence.
Quote #3
But his seeing it she didn't mind a scrap, and not a scrap either his knowing how she had left the dear lady [Susan] in the dark. She had come alone, putting her friend off with a fraud: giving a pretext of shops. (1.5.3.26)
Milly doesn't care if Sir Luke knows that she has deceived her Susan. Actually, Sir Luke appreciates Milly's efforts to be independent and to live life on her terms. It's part of his patented "live life to the fullest" cure.