Why should a set of people [a family] have been put in motion, on such a scale and with such an air of being equipped for a profitable journey, only to break down without an accident, to stretch themselves in the wayside dust without a reason? (18.104.22.168)
Kate Croy's family has completely disintegrated. Her mother is dead, her father is absent, and her sister is widowed with four children to support. Kate is really the only one who's ended up okay by being taken in by her rich Aunt Maud. But Kate still assumes that family should give stability to life, not create chaos. She must have learned that one from a fairy tale rather from her own experiences.
When her father at last appeared she became, as usual, instantly aware of the futility of any effort to hold him to anything." (22.214.171.124)
Kate is in the unfortunate position of loving her father but not trusting him. The man has essentially spent his whole life lying about everything, and this causes severe long-term emotional issues for Kate. What a shocker, right? She responds to his dishonesty and shiftiness by developing a fairly cynical view of the world. This makes her a little unlovable at times.
The hitch here, of course, was that, with whatever beauty, her sister, widowed and almost in want, with four bouncing children, was not a sensible value." (126.96.36.199)
Kate Croy's father Lionel doesn't much like his other daughter, Marian. He more or less thinks that she's worthless because she's an aging widow with four kids. For Kate, though, there's still hope. But what kind of hope, you ask? Well for Lionel, it seems that his main idea of "value" is for his daughter to marry rich and send him some money.
"[Aunt Maud] wants me to choose. Very well, I will choose. I'll wash my hands of her for you to just that tune." (188.8.131.52)
At the beginning of the book, we learn that Aunt Maud has commanded Kate never to see her father again. Kate, however, is ready to walk away from all of Maud's money in order to be with her father. She does this in spite of the fact that Lionel Croy treats her like dirt and totally rejects her affection. His treatment of her will leave lasting emotional scars that help explain Kate's selfish, cynical behavior throughout the rest of the book.
Mrs. Lowder was her only 'real' aunt, not the wife of an uncle, and had been thereby, both in ancient days and when the greater trouble came, the person, of all persons, properly to make some sign. (184.108.40.206)
Aunt Maud is Kate's only "real" aunt, meaning that she is a direct blood relative. And according to the narrator, this makes her the right person to offer help to Kate when her core family implodes because of her jerky Daddy-O. Here, the book is suggesting that in Edwardian England, blood ties are taken super-seriously.
"The tune," she exclaimed, "to which we're a failure as a family!" (220.127.116.11).
Kate has no illusions. She knows that she comes from a broken home. She opens herself up emotionally in order to tell Merton this, because deep down, she feels like she needs to give a reason for why she is the way she is—bossy, cynical, and defensive. Whether or not you accept her past as an excuse for her present is up to you.
"And yet it's a part of me," said Kate.
"A part of you?"
"My father's dishonor." (18.104.22.168-32).
Kate knows that her father's terrible legacy won't end with his death. His cruelty lives on in his daughters, whose personalities have been shaped by his terrible treatment. Both, for example, have long-standing trust issues. They believe they should serve only themselves because people like their dad will always be out there to take advantage of them.
"My niece and her affairs—that I should have to say such things to-day!—are a constant worry; so that Kate, in consequence—well, of events!—has simply been called in." (22.214.171.124)
Aunt Maud informs Merton that Kate, against Maud's wishes, has gone to visit her sister Marian for the holidays. Aunt Maud would prefer it if Kate didn't see her family anymore, since Maud believes that these people will infect Kate with their negativity. But Kate, always the loyal daughter and sister, can't turn down a call for help from blood relatives.
"They've the misfortune to have, I suppose you know, a dreadful, horrible father." (126.96.36.199)
Maud is no stranger to Lionel Croy's terrible ways. In fact, she bans Kate from ever seeing him again, a command that Kate totally disobeys. Maud knows that Lionel is bad for Kate, but also understands Kate's yearning to start over and to create a relationship with her father that she never had growing up.
"If you love me—now—don't ask me about my father." (188.8.131.52)
When Merton comes to Marian's to see Kate, he asks how Kate's father is doing. But Kate, as tortured as she is, pleads with Merton to never, ever, ask about her father. Lionel Croy is the main reason Kate has such a tough time loving, and to talk to Merton about Lionel is, in Kate's mind, to link them. She prefers to keep them separate from one another and to think of Merton as different and kind.