Nikki Walsh could give Joan Crawford a run for her money—she is the ultimate in unpredictable and violent moms. Instead of having warm and fuzzy memories about his mother, Matthew's memory lane in filled with incidents like the one in which she holds a knife up to his neck for taking an Oreo without asking first. That's certainly not normal behavior:
"Thief!" our mother yelled. "Cookie thief!" She burst into giggles.
She had the big kitchen knife, and it was pressed to my throat. And as she laughed, I could feel it shake in her hands, and push against my skin.
She cut me that night. Just a little. (2.6-8)
Because of her horrible behavior, the kids don't bond with Nikki as though she's a "normal" mom. Instead, they are constantly afraid of her and relieved when she disappears for days on end. They don't want her around; it's simply safer to have her far away.
The scary thing is that the kids never really know why Nikki lashes out at them. Matthew often wishes that he could explain his mother's behavior, but he soon realizes that this is just the way life is—sometimes, you don't get a neat explanation for why bad things happen.
Nikki isn't just terrible when it comes to her kids. She is also a devious, sneaky person in other areas of her life. Because she's physically attractive, Nikki can often trick men into dating her; she is also well-versed in lying as a means to get her way. When she gets mad at Murdoch for being distant, for instance, she drops off all her kids at his house and makes up some story about how a friend has an emergency. Of course, this is all a lie:
There had been no telephone call from Rebekah—the phone hadn't rung at our apartment all night. And as to our mother not wanting to leave us home alone, well, it had never bothered her before. (11.23)
And Murdoch sees right through her lies, which is why he eventually breaks up with her. Nikki isn't able to hang onto healthy relationships because she cannot be honest and giving in them. Instead, she constantly just lies in order to benefit herself—without any thought for anyone else. Even Aunt Bobbie admits that Nikki has always been this way:
And this is where Aunt Bobbie surprised me for the first time. "Nikki was a big liar when we were kids," she said thoughtfully. "I can't even remember how many times she got me in trouble, saying I'd done things I hadn't."
"Liar," you said intensely. (27.39-40)
Nikki is not one to be trusted, and no one knows that better than her very own family.