Having heard Vicki Laveau-Harvie interviewed on Conversations with Richard Fidler before I read her Stella prize-winning debut, The Erratics, I thought it odd that the host was having a chuckle about her story: a mother whose psychological cruelty knew no bounds, a father barely aware of her existence, and a childhood spent vainly trying to please. While Laveau-Harvie’s warmth and good humour came across, her book sounded like misery memoir. But no. Her agile humour – albeit of the gallows variety – transforms it into something quite of its own genre.

Laveau-Harvie was estranged from her parents for 18 years before she and her sister travelled back to Southern Alberta to check on their wellbeing – and discovered their mother had been starving their father. In the face of doubting health workers, who seemed to swoon into their mother’s fantastical stories (including that she had only one daughter, now dead; that she had 18 children; and that Laveau-Harvie is part of a South American drug syndicate, wanted by Interpol) they must hold steady and get her diagnosed and sectioned to prevent her from finishing off their father.

It occurs to me that she is a kind of flesh and blood pyramid scheme, a human Ponzi. You buy in and you are hooked.

This kind of manipulation is nothing new to Laveau-Harvie. When she was growing up, legions of friends and neighbours were ostracised by her mother, further and further isolating the family. Her mother repeatedly regarded the girls with a strange kind of sorrow, observing, “I’ll get you and you won’t even know I’m doing it.” Once, she cut off Laveau-Harvie’s ponytail with sewing shears in a fit of spite.

What did she do with the ponytail she sheared so close to my scalp? It must have lain intact in her hand, still held together by the elastic I had wound around it that morning. I wonder what she did next, because I do not remember. From that moment on and for a period after that, from the moment of cold metal against the back of my head and the crisp whisper of the blades closing, I remember nothing.

Small wonder that the retired academic and translator had moved as far away from her parents as she could, to Australia. The Southern Alberta she describes is marooned by snow drifts and grasslands – “In winter the cold will kill you. Nothing personal” – and it is there that her besotted father retreated with her mother, holed up in a fortress stuffed with fur coats and oil paintings. The sisters discover their mother has been further squandering his money, sending cheques to scammers across the globe. Their arrival at the ranch is met with outright hostility, threatening to burst this bubble of two.

What great freedom is awarded to a memoirist with no loyalties to answer to. Laveau-Harvie chooses not to probe into the backstory of her parents, and why should she? Having endured so much, she has no responsibility to concern herself with motives. Similarly, while in Fidler’s interview she acknowledged her mother’s narcissistic personality disorder, she doesn’t explore the diagnosis in the text.

Unlike her sister who still longs for Hallmark moments, Laveau-Harvie has long since clinically disengaged herself from “the people who begat us”, which creates a chasm between the siblings. (For shorthand, recall the sitcom Roseanne and the neurotic Jackie in comparison to the titular dispassionate protagonist, mixed in with the freezing black comedy of Fargo.)

From the first chapter, she takes the calculated risk of readers disliking the pair, as the extent of their mother’s gaslighting is not yet known, only the displeasure of the offspring. Laveau-Harvie’s observations are the impish voice in the head, making judgments that no one must ever hear (although you suspect in her case this kind of humour is not so much defence mechanism as survival mechanism). It’s a head-voice so familiar that when she periodically addresses chronological disparity in the book by breaking the fourth wall – “Come back in time with me to 18 months before this New Year’s Eve in Hong Kong” – the effect of being cleaved from her usual tone is jarring.

The Erratics doesn’t drip with pathos or gaze shudderingly into its navel, and yet there are moments of tenderness springing up like flowers in a melting snowscape. In a rare moment of parental consideration, Laveau-Harvie finds her father’s paisley dressing gown left out for her to wear. “I bury my face in it, hoping for a hint of his soap or his aftershave, but it smells of nothing.” Of the relatives who come flocking to help, she says, “I have done nothing to deserve the kindness these people show me.”

As time wears on as the siblings strive to organise their parents’ home for their father to live independently – a difficult task, when tradespeople and taxi drivers refuse to come, having been burned before – Laveau-Harvie loses her sense of self. As a child she wondered if she had a doppelganger, so fictitious were her mother’s accounts of her. Now she feels transparent, like a wonton wrapper in a steamer basket.

With the publication of The Erratics, Laveau-Harvie finally gets to control her own narrative (deservedly it was picked up by HarperCollins for a second lease of life after going out of print). Once her mother is finally assessed and committed, the grief comes, and she is able to let it. It’s as though, all this time, she’s been holding her breath.

• The Erratics by Vicki Laveau-Harvie is out now through HarperCollins