An obsessive stalker, an impotent husband, a lover of young boys... to some, the creator of 'Peter Pan' was an evil genius; to others, a misunderstood ingenue. Ever mindful of the J.M. Barrie 'curse', Justine Picardie investigates

'May God blast anyone who writes a biography of me,' declared J.M. Barrie, in a curse scrawled across the pages of one of his last notebooks. Since his death in 1937, this dire warning has not prevented a slew of writers taking him on, the latest of which is Piers Dudgeon, whose book Captivated is subtitled The Dark Side of Never Never Land, and examines what he believes to be Barrie's sinister influence over the du Maurier family.

Dudgeon's portrait of Barrie - as a man who filled the vacuum of his own sexual impotence by a compulsive desire to possess the family who inspired his most famous creation, Peter Pan - is entirely at odds with the Hollywood version, Finding Neverland, in which Johnny Depp portrayed the author as a charming hero, devoted to large dogs and small children. Here was the quirky little man who had already been celebrated by his contemporaries as a genius with a great heart, not least for his bequest of the copyright of Peter Pan to Great Ormond Street Hospital for Children, thus ensuring that the golden fairy-dust of his writing was liberally sprinkled over those in need.

But where does the truth lie about J.M. Barrie

• (an author who explored the shadowy borderlands where truth and lies mingle and breed)?

At this point, I should confess to having become absorbed in Barrie's life while I was researching Daphne, a novel about Daphne du Maurier and her family; although I tried to keep Barrie on the very outer edges of my book

• (?let him come any closer, and he would have dominated the action, for his story is so extraordinary that it would push everyone else's aside).

From the beginning, his life was marked by tragedy: born in Kirriemuir in 1860, the child of a Scottish weaver, he grew up in the shadow of an older brother, David, his mother's adored golden boy, who was killed on the eve of his 14th birthday in a skating accident.

Dudgeon makes the startling suggestion that Barrie was involved in his brother's death, and whether or not this accusation is true, the calamity shaped him as a writer, for as an author he brought to life the myth of the perfect boy who never grows up, who can fly out of danger, and yet for whom death would be 'an awfully big adventure'.

If I'm honest, I was also spooked by Barrie's curse, after hearing what had happened to the writer Andrew Birkin. In his updated introduction to the most recent edition of J.M. Barrie and the Lost Boys, Birkin wrote, 'I feel somewhat felled by Barrie's curse', for his son had been killed in a car crash, one month before his 21st birthday, the same age that Barrie's adopted son, Daphne's cousin Michael, had drowned. Sceptics will doubtless scoff at my superstition, but as the mother of two teenage sons, I didn't want to incur the posthumous wrath of Barrie.

Yet even though I avoided using precise details of Barrie's life in my novel, it was impossible to ignore him while I was immersed in researching the book

• (in the du Maurier family archive at Exeter University, amongst other sources).

For any account of the du Mauriers is bound to collide with Barrie, as their lives entwined as much as the fictions that they made out of their lives.

Daphne's father, Gerald du Maurier, was Barrie's favourite actor, and fell in love with her mother, Muriel, when they starred as the romantic leads in a Barrie play, The Admirable Crichton. Gerald also played Captain Hook and Mr Darling in the first production of Peter Pan on 27 December, 1904 (reprising the roles in annual Christmas revivals); and Daphne's older sister, Angela, subsequently appeared as Wendy.

Most important of all, it was Gerald's sister, Sylvia - played by Kate Winslet in Finding Neverland - who was the mother of the five 'Lost Boys' that inspired Peter Pan. Their father was a handsome barrister, Arthur Llewelyn Davies, and Sylvia was celebrated as one of the great beauties of the day. The couple had five sons:

• George (named after Sylvia's father, the writer and artist George du Maurier), born on 20 July, 1893;
• Jack, born on 11 September, 1894;
•  Peter, born on 25 February, 1897, named after George du Maurier's novel, Peter Ibbetson;
• Michael, born on 16 June, 1900; and
• Nico, born on 24 November, 1903.

Barrie first met the two oldest Llewelyn Davies boys when George was five, and Jack a year younger, as they played in Kensington Gardens, close to their parents' house. He had a wife by then, a pretty young actress named Mary Ansell but, after four years of marriage, they were still childless, instead lavishing their affections on Porthos, a St Bernard dog named after the St Bernard in Peter Ibbetson.

• (You'll notice by now that fact and fantasy are threaded inextricably together in the relationship between Barrie and the du Mauriers.)

Certainly, Barrie was a great admirer of George du Maurier - the best-selling author of Trilby, as well as of Peter Ibbetson, and a renowned illustrator for Punch - though no record remains of the pair ever meeting. But Dudgeon believes that Barrie was sufficiently obsessed by George du Maurier - in particular, his talent for hypnosis, or 'the gift of the devil', explored in Trilby through the evil character of Svengali mesmerising his female victim - to have set about stalking Sylvia and her children, thereafter exerting mind-control over both them and Daphne du Maurier (who, like her two sisters and their boy cousins, knew Barrie as 'Uncle Jim').

Thus Dudgeon's interpretation of Barrie's adoption of Sylvia's boys, who were orphaned after their mother died of cancer in 1910, three years after their father succumbed to the disease, is an entirely dark one. And taking his cue from D.H. Lawrence's observation, 'J.M. Barrie has a fatal touch for those he loves. They die', Dudgeon sees Barrie as being eerily associated with the tragedies that befell the family after he befriended them:

• first Arthur and Sylvia's early deaths,
• followed by that of George, as a young soldier in the First World War in 1915,
• then Michael's drowning (widely held to have been a suicide) as an undergraduate at Oxford in 1921;
• Daphne's breakdown in 1957;
• Jack's death from lung disease in 1959; and
• Peter's suicide in 1960.
• (Only Nico escapes the shadow of Barrie, according to Dudgeon's account, by virtue of his unusually sunny personality.)

It's an imaginative theory, which draws on some circumstantial evidence in Daphne du Maurier's own writing

• (including her macabre short stories, which Dudgeon reads as revealing Barrie's crimes),

and will be of interest to anyone, like me, who has followed the twists of the du Maurier family history.

Indeed, Kits Browning, Daphne's son, declares Dudgeon's book to be 'absolutely fascinating, though somewhat alarming about the extent of Barrie's sinister influence on my family'. Inevitably, there are detractors: Jack Llewelyn Davies's granddaughter, Henrietta, bristles at the mention of Dudgeon's book.

• 'It's far too simplistic to cast Barrie as an evil genius,' she says. 'My grandparents used to describe him as a sympathetic and sensitive soul. The bottom line is that he was a lonely man who did everything for the boys he'd adopted, who he adored. He was a human being who did his best by them...'

Similarly, Nico's daughter, Laura Duguid - also Barrie's godchild - is more affectionate than damning in her recollections of him. Now 80, she remembers being taken to spend an afternoon with her godfather (by then a baronet) at his flat on the top floor of Adelphi Terrace House, overlooking the Thames.

• 'Usually I was a feeble little girl,' she says, 'who needed Mummy or Nanny. But I remember having a wonderful afternoon with Barrie - and being surprised at myself for not minding being left alone with him. He told me stories and chased me around the dining table. And, of course, my father thought Barrie was the most marvellous person with children - hence him asking him to be my godfather, and being happy to leave me alone with him.'

She also quotes me her father's view on Barrie's sexuality (or lack of it):

• 'I don't believe that Uncle Jim ever experienced what one might call a stirring in the undergrowth for anyone - man, woman, adult or child. He was an innocent...' This is a view shared by Andrew Birkin, who has probably studied more of Barrie's letters and notebooks than anyone else alive (he was given complete access to them by Nico, who died in 1980): 'Yes, of course Barrie was a lover of childhood, but was not in any sexual sense the paedophile that some claim him to have been.'

And yet, as Duguid acknowledges, there are passages in Barrie's writing that induce a sense of unease.

• 'I'm certain that there was nothing paedophiliac about him,' she says, 'but he did write some creepy things in The Little White Bird.'

She is referring to Barrie's novel, which contains the original story of Peter Pan, while also apparently chronicling his relationship with the young George Llewelyn Davies, for whom Barrie had invented Peter Pan.

According to Birkin, 'The book is narrated in the first person by Barrie', thinly disguised as Captain W, who also happens to be a writer, given to long walks in Kensington Gardens with his St Bernard dog, Porthos. George is transformed into David (the name of Barrie's dead brother), while his fictional mother, Mary (the name of Barrie's wife), is closely modelled on Sylvia.

Meanwhile, the Captain seeks to assuage his thwarted paternal yearnings by winning the boy for himself:

• 'It was a scheme conceived in a flash, and ever since relentlessly pursued - to burrow under Mary's influence with the boy, expose her to him in all her vagaries, take him utterly from her.' Mary, however, remains 'culpably obtuse to my sinister design'.

All of which may give some insight into why Barrie's original title for the story of Peter Pan was The Boy Who Hated Mothers.

When The Little White Bird was published in 1902, it was hailed by The Times Literary Supplement as

• 'an exquisite piece of work' and 'one of the most charming books ever written'. The same review also declared,
•  'If a book exists which contains more knowledge and more love of children, we do not know it.'

But a modern reader might feel less straightforwardly celebratory. Take, for example, the following passage, when the narrator describes his night alone with the child:

• 'David and I had a tremendous adventure. It was this - he passed the night with me... I took [his boots] off with all the coolness of an old hand, and then I placed him on my knee, and removed his blouse. This was a delightful experience, but I think I remained wonderfully calm until I came somewhat too suddenly to his little braces, which agitated me profoundly... I cannot proceed in public with the disrobing of David.'

After some time, David climbs into bed with the narrator.

• 'For the rest of the night he lay on me and across me, and sometimes his feet were at the bottom of the bed and sometimes on the pillow, but he always retained possession of my finger...'

• 'this little boy, who in the midst of his play while I undressed him, had suddenly buried his head on my knee' and of his 'dripping little form in the bath, and how when I essayed to catch him he had slipped from my arms like a trout.'

Gerald du Maurier's biographer, James Harding, was made decidedly uncomfortable by this scene, though veered away from any accusation of impropriety.

• 'One needs a tough stomach to put up with Barrie in this mood,' he wrote, in 1989. 'No writer today would publish such an account without inviting accusations of paedophilia or worse. Yet Barrie, in the manner of Lewis Carroll and his nude photographs of little girls, was consciously innocent. His snapshots of the tiny lads [the Llewelyn Davies boys] frolicking bare-bottomed on the beach, the cowboy and Indian adventures he made up for them... were a means to enjoy the pleasures of fatherhood with none of the pains. In Sylvia du Maurier's children he discovered the ideal outlet for the frustrations which obsessed him.'

Dudgeon is unconvinced by Harding's phrasing - 'How did he know that Barrie's innocence was conscious?'- but there is still no evidence to settle the argument. Having read Dudgeon's book, and re-read Birkin's, and then returned to my own research notes from the du Maurier archive and elsewhere, I remain just as uncertain about J.M. Barrie, whose chief aim seemed to be not to corrupt boys into adult desire, but for himself to rejoin them in the innocence of eternal boyhood, a Neverland where children fly away from their mothers and no one need grow old.

True, there are letters of his that are odd, such as the one he wrote to Michael on the eve of his eighth birthday, in June 1908:

• 'I wish I could be with you and your candles. You can look on me as one of your candles, the one that burns badly - the greasy one that is bent in the middle. But still, hurray, I am Michael's candle. I wish I could see you putting on the redskin's clothes for the first time... Dear Michael, I am very fond of you, but don't tell anybody.'

This is one of the few letters that have survived - Peter Llewelyn Davies destroyed nearly all of Barrie's vast correspondence with Michael in the melancholic period before he killed himself by diving under a Tube train at Sloane Square station.

• ('They were too much,' was his only comment on the letters between Barrie and Michael.)

Elsewhere, there are moments when Barrie seems to display an unsettling streak of casual sadism

• (not dissimilar to Peter Pan, whose capacity for cruelty was eradicated in the Disney version).

For example, in The Little White Bird, the narrator declares,

• 'I once had a photograph taken of David being hanged on a tree', which he sends to the child's mother: 'You can't think of all the subtle ways of grieving her I have.'

Given that Barrie's fame coincided with Freud's, it is surprising that no one analysed his motives at the time.

Yet Sylvia, like the parents of the other children befriended by Barrie, welcomed him as a kind of benign fairy godfather, even when he adopted the persona of the pirate Captain Swarthy (an early incarnation of Hook), and forced a four-year-old Peter to walk the plank into the murky waters of Black Lake, in the forested grounds of the Barries' holiday retreat in Surrey.

Perhaps Arthur was less keen on Barrie - though he seems to have accepted the author's presence within his family as he grew closer to death - and Sylvia's true feelings at the end of her life remain unclear. Barrie, by then divorced, told her son Jack that Sylvia had agreed to marry him on her deathbed; a story that neither Jack nor Peter believed.

He also - and this is the most damning piece of evidence against him - rewrote Sylvia's will to make it appear that she had wanted him to care for her orphaned boys. In reality, Sylvia had left a handwritten document, which said:

• 'What I wd like wd be if Jenny wd come to Mary & that the two together wd be looking after the boys & the house.'

Mary was the boys' longstanding nanny, whom Sylvia trusted above all others, and Jenny was Mary's sister. But after the will was found, Barrie transcribed it himself and sent it to the boys' maternal grandmother, having altered Jenny to Jimmy, so it appeared that Sylvia wished him to become the boys' guardian.

Birkin observes that the 'transcription was no doubt unintentional'; Dudgeon sees the alteration as an indication that 'Barrie's strategy was predatory.' Whatever the reason, the boys became Barrie's own.

Many years later, in 1946, Peter wrote a letter suggesting that in the wake of his parents' deaths, he and his brothers were

• 'spirited away, as children, from my mother's and father's friends... the whole business, as I look back on it, was almost unbelievably queer and pathetic and ludicrous and even macabre in a kind of way...' ?

Yet he also admired Barrie, and the creation that was his namesake, describing Peter Pan as 'that terrible masterpiece'. There is a faint echo in his words of those previously put into his mouth by Barrie, who had whimsically named him as the four-year-old 'author' of an early version of Peter Pan, The Boy Castaways of Black Lake Island, a privately printed edition which included Barrie's photographs of George, Jack and Peter's adventures with Captain Swarthy in August 1901, 'that strange and terrible summer...' Barrie kept one copy for himself, and gave the other to the boys' father, Arthur, who promptly mislaid it on a train

• (an act which was, observed Peter in adulthood, 'doubtless his own way of commenting on the whole fantastic affair').

In his dedication to Peter Pan, written over a quarter of a century afterwards, when two of the Boy Castaways were dead, along with their parents, Barrie referred to that early book as

• 'the rarest of my printed works... for the only edition was limited to two copies, of which one (there was always some devilry in any matter connected with Peter [Pan]) instantly lost itself in a railway carriage.'

In the end, perhaps the last word should go to J.M. Barrie, who remains as tantalisingly elusive as Peter Pan himself, and perhaps as devilish, and also as expressive of childhood innocence

• (the two are not mutually exclusive, particularly in a writer of genius).

In that same dedication, he referred to someone who might be Peter Pan, or possibly his creator; or maybe the two combined:

• 'that sly one, the chief figure, who draws farther and farther into the wood as we advance upon him. He so dislikes being tracked, as if there were something odd about him, that when he dies he means to get up and blow away the particle that will be his ashes.'

Justine Picardie will be talking at the 'Ways with Words' festival at Dartington Hall, Devon, on 15 July

• See a comment: "JM Barrie now seen as "a monster", by Gilbo