If your heart spoke, what would it say?

In 2005, when Maggie Nelson’s book Jane: A Murder was published, she received a letter from a homicide detective. He had gone through the book with a highlighter pen, he said, and added: “I can honestly say it’s the first book of poetry I’ve ever read”. Nelson replied that it was the first book she’d ever written to be highlighted by a homicide detective.

The exchange is a stark illustration of the line Nelson treads between fact and form. Jane – an inventive, delicate, searing book – took as its subject the murder of Nelson’s aunt at the age of 23. She was killed in 1969, two years before the birth of Nelson’s sister Emily, and four years before Nelson’s; Jane’s legacy hung over the family, and over Nelson specifically, who was routinely mistaken for Jane by her grandfather. Nelson came to identify with Jane so closely that when she found her diary, she thought at first it was an old one of her own.

“I think that book’s greater theme,” Nelson tells me, over the phone from her home in Los Angeles, “in addition to violence or fear, is the excitements and perils of learning about yourself through twinning and doubling – my sister and me, my mother and Jane, Jane and me.

“That moment when you say: ‘Oh my gosh, we’re so much alike!’ can be very illuminating and very bonding, but it can also be very distorting. I never knew my aunt – so it’s really about me. That dance of projection and communion was compelling to me.”

The book’s publication was already imminent when the detective got in touch to tell the family that this 35-year-old case, which they had always assumed would remain unsolved, was close to being brought to trial. All the time Nelson had been lending her imagination to the story, Detective Schroeder had been following leads based on DNA.

“I bet you thought you were working on this alone all these years,” he said. And so, almost immediately, another book was born. The Red Parts: Autobiography of a Trial follows with extraordinary emotional control her family’s reliving of the old trauma, and documents some others along the way: not least her father’s sudden, fatal heart attack, when she was 10 years old.

Until recently, Nelson’s writing career has been conducted on the cooler fringes of philosophy, poetry and academia. But her last book, The Argonauts, brought her from the underground into something closer to the mainstream. It seems, in retrospect, a curious transition: published in 2015, The Argonauts, the title of which is borrowed from a passage in a book by Roland Barthes, also steals the structure of Barthes’s late work, A Lover’s Discourse: Fragments, and quotes liberally from thinkers such as Julia Kristeva and Anne Carson, their names dotted in the margins.

The topic? Nelson’s relationship with Harry Dodge, who is fluidly gendered and with whom she sleeps before she knows which pronoun to use in relation to him. Over the course of the book, Harry has surgery to remove his breasts and starts taking male hormones, while Maggie becomes pregnant with their child. The book instantly struck a nerve: intimate, honest and unafraid of critical thought, it was praised by reviewers all over the world, and was shortlisted for this week’s Rathbones Folio prize.

Now two of Nelson’s earlier books – The Red Parts and Bluets – are being published in the UK for the first time, which has the curious effect, for the British reader, of reading her backwards. The Red Parts was originally published in 2007; Bluets, which was released in 2009, describes a love affair that took place between 2003 and 2006. Ostensibly a meditation on the colour blue, it’s really about a heartbreak suffered by a person who once thought she might write about the colour blue.

Various blue objects, instances and emotions have been collected, and assembled like impractical relics around her ongoing distress at the hands of a man she calls “the prince of blue”, who has left her for another woman.

Like The Argonauts, the book is graphic in its depiction of sexual desire, but Bluets is much more solipsistic. “Eventually you will have to give up this love,” the narrator’s friend tells her halfway through the book. “It has a morbid heart.” At the end, she still hasn’t.

Nelson says she writes about many different things, and she’s pleased more readers now have the opportunity to discover her range. But the consistencies are perhaps more intriguing. In a new preface to The Red Parts, she writes that she’s glad of the chance, “once again, to send in this report from the field”.

That, more than anything, is Nelson’s project: to behave as though the land of the heart were automatically a subject for reportage, and not just a cause for an outpouring of emotion. Heartbreak, longing, sex, death, fear, family trauma, love, maternity, homonormativity: these are the territories from which Nelson has chosen to deliver her dispatches. If that sounds merely confessional, the books are far from it.

The great distinction of Nelson’s work is that it is both truthful and confected. While The Argonauts took its formal structure from Roland Barthes, Bluets borrowed the architecture of Wittgenstein’s Philosophical Investigations. There is a “miniature feminist project in there”, Nelson suggests: “Wittgenstein apparently had a lot of agony around the personal and the sexual and the bodily – he writes a lot about pain. It was interesting to take some of his locutions through this content that would have probably been horrifying to him.”

Nelson’s interest in form might be traced to her beginnings as a poet. “I think of the ‘I’ as a character that I’m controlling in a certain way,” she explains. Bluets starts with the line “Suppose I were to begin…” and that, she reflects, is designed to signal “that this is going to be a speculative eye”. At

Maggie Nelson is writing about t emotion in a way no-one else ever has, says Gaby Wood

ostensibly a meditation on the colour blue, is really about heartbreak

‘ I have come at autobiography from a different angle’: Nelson at home in LA