Mothers have always inspired French-Canadian writer and director Xavier Dolan.

His first film was the semi-autobiographical I Killed My Mother (2009), in which he also starred as a 16-year-old in conflict with mother Chantal (Anne Dorval). Five years later, the theme of motherhood returns in his newly released Cannes Jury Prize winner, Mommy, in which Dorval stars again as the film’s heroine, Diane ‘Die’ Després. In between these maternal melodramas he’s made three other films – Heartbeats (2010), Laurence Anyways (2012) and Tom at the Farm (2013). Each features formidable women and challenges aplenty to gender and sexual norms, yet the most imposing figure in Dolan’s universe remains the mother. She is, in his own words, the figure he knows more than any other; his own mother but also ‘the mother at large,’ the figure he always returns to, ‘it’s her, no matter what, who’ll have the last word’.

Mommy takes place in a working-class Québec suburb and focuses on Die, a widow, and her 15-year-old son Steve (Antoine-Olivier Pilon). We first meet Steve coming home after a stint in an institution for troubled youth. He suffers from ADHD, with violent tendencies and an emotional attachment disorder. He’s set the cafeteria on fire and injured another boy. Even before we meet him, we know he’s trouble.

Where I Killed My Mother was an adolescent’s view of mothering as hostile act, Mommy privileges the mother’s experience without ever sentimentalising it. Die is tough, and believes that if she loves Steve fiercely enough she can fix him. She learns her mistake the hard way – once back at home, Steve is unpredictable, wild and even terrifying. And yet, mother and son remain fiercely loyal to one another. They are each other’s whole world. Dolan establishes this in part through Mommy’s powerful use of the 1:1 ratio, reducing screen space to a box. This is not a gimmick, but a way to visualise the compressed borders of their world. And he traps us right in there with them.

Dorval possesses the burning, force-of-nature intensity of a contemporary Anna Magnani. She brings a moving and challenging ferocity to this, her third collaboration with Dolan. While a briefly glimpsed photo suggests a ‘classier’, more conservative past, the Die we meet looks like a teen princess – heavy make-up, platform shoes, bejeweled jeans and too-tight tops, her speech peppered generously with expletives.

But this is all part of her earthy package, and Dolan doesn’t judge her. It’s clear he loves his character, and wants his audience to as well. Although Die lives on the margins, Dolan won’t let her be invisible, silent or decorative. He gives her soul, will and strength, and anchors her in a world we all recognise, where the meat of everyday life is a struggle. Die is not a victim – her aspirations for her son remain big and expansive, even if circumstances have reduced her to filling gift bottles of wine from a never-ending cheap cask.

One of these bottles is delivered to Kyla (Suzanne Clément), Die’s new neighbour, who intervenes in a particularly volatile clash between mother and son and swiftly becomes an integral part of their world. Kyla’s got problems of her own. She’s on a sabbatical from her job as a teacher, having suffered some kind of trauma – she struggles to speak, and when she does it’s with a stutter. Mothering Steve is too great a job for one person, and an intense and generous friendship develops between Die and Kyla. Unlike so many female relationships in mainstream cinema, their bond isn’t constructed relative to a romantic pursuit – they do not compete for a man’s attention, but find solace and strength in each other. Kyla homeschools Steve so Die can return to work, and in turn mother and son help her to recover her voice and joie de vivre (even if that involves singing and dancing to Céline Dion).

Die will do anything for her child. Not one for tempering the melodrama, Dolan allows her to indulge in a fantasy vision of her son’s future life (one of two points during Mommy in which he stretches the screen to its normal ratio, to powerful effect). But Dolan also acknowledges the limitations of sentiment – while it’s a scene of operatic proportions, it’s ultimately an impossible, tragic dream. A mother’s love can’t conquer all.

When the history of cinema is rewritten, Dolan will have a place beside Douglas Sirk, Todd Haynes, François Ozon and especially Pedro Almodóvar, as a great male director of women. He’s already Almodóvar’s likely heir – each has created an exuberant body of cinema that privileges women (and others on the margins) as complex, chaotic beings. In All About My Mother (1999), Almodóvar gave us bold females (both biological and not) who were many things at once – mothers and whores, saints and sinners, and everything in between. Similarly, Dolan’s fierce mothers are cleaved from the pedestal that so much of cinema places them on, so that they may dig around in the dirt that is life. And it’s a magnificent mess to watch.