It was shortlisted for this year's Waterstones Children's Book Prize and the Children's Books Ireland Book of the Year and won the inaugural Young Adult Book Prize, while The Irish Book Awards named O'Neill newcomer of the year. In the US it sold out on pre-order and was reprinted before its publication in May. Small wonder, then, that her publisher, Quercus, convinced of the book's crossover appeal, will bring out an adult edition next month, an honour previously bestowed on the likes of J.K. Rowling and Suzanne Collins, author of The Hunger Games.
"I'm trying not to get too caught up in it all," O'Neill says. "I'm really grateful that people understand the work and the message I'm trying to put across, because I felt passionately that we needed to talk about the way in which we view women's bodies. We spend our lives looking at images of 6ft tall, size six Victoria's Secret models and our self-esteem and self-worth starts to dip. I'd say that of the women I know only three or four aren't affected in some way by the idea that they should look a certain way. Many women make a correlation between moral worth and weight and I really wanted to explore that. I didn't set out to write a young adult novel when I wrote Only Ever Yours but I was in a way writing for myself at 16."
That willingness to tackle dark and difficult themes - her second novel, the brilliant, harrowing Asking For It, expected out later this year, is set in present-day Ireland (O'Neill is from the small town of Clonakilty in County Cork) and focuses on a rape at a party - has placed O'Neill at the forefront of a young adult publishing revolution. For it's not just that young adult novels are among the most popular genre in publishing (being read by teenagers and adults of both sexes), it's that increasingly they are tackling important issues with honesty, humour and a steely precision that other supposedly more serious novels frequently lack.
Thus, Becky Albertalli's Simon Vs The Homo Sapiens Agenda is a subtle, affecting look at a young gay teenager's first steps towards coming out, Lisa Williamson's The Art Of Being Normal tells the moving story of a young transgender teen, Naomi Jackson's The Star Side Of Bird Hill looks at notions of race and identity as two sisters move from Brooklyn to Barbados, while Keris Stainton's Reel Friends series depicts teenage female friendships that feel modern and utterly true.
"There's definitely a difference in how young adult books are portraying female characters," says O'Neill. "They're more aspirational in that they present more of a reflection of something a teenage girl can look up to, saying this is what a healthy and positive relationship looks like. This is a healthy and positive way to be a girl."
Not that they're shying away from dark themes. "Oh God, no," says O'Neill. "I decided to write Asking For It because I wanted to talk about the idea that rape isn't just being pulled into an alleyway by a stranger, that there are many different levels. All of my friends have stories of sexual assault and sexual experiences that weren't right. They'll say 'this is what happened when I was 17' and the terrible thing is, I'm not surprised. I'm not surprised that they were sexually assaulted, or raped, that their drinks were spiked or they were too drunk to consent. We need to talk about the idea that sex isn't something that men forcibly take from women. We tell girls 'don't get raped', when we should be teaching boys 'don't rape'."
Her books are equally unflinching about life in the social media age. "Social media is a double-edged sword," says O'Neill, herself an enthusiastic user of Twitter. "There are extremely positive elements to it, particularly the way in which it makes it easier for us to connect and build our own communities. Even selfies can be positive - I think there's something brave and amazing about teenage girls posting pictures of themselves saying, 'This is how I look and I am beautiful' but it's also true that it can exacerbate feelings of not being good enough. There's so much toxic competitiveness when you're a teenage girl - 'Are my thighs smaller than hers?' 'Am I prettier?' 'Do boys like me more?' Social media adds to the pressure and then society tells young women that they must look sexy and act sexy but that they can't be sexual beings."
Comments such as this help explain why O'Neill's books are read as much by the anxious mothers of teenage girls as by the girls themselves. "The key is to be honest," she says when asked what advice she would give those parents. "I would hope mothers who read my books understand the pressures their daughters are under and why they are acting or behaving the way they are. Try to encourage honest communication, be open and interested, try to understand."
And what would she tell the teenagers of either sex who devoured Only Ever Yours? She laughs. "The most important thing is to care less about what other people think of you and focus more on yourself, your values and ethical system, then live according to that," she says.
"It sounds very 'to thine own self be true' but it's the only way to live. When I wrote Only Ever Yours it was at a time when I was so sick and tired of feeling shame around my body and so weary of fighting the fact that women are seen as less in so many ways. I wanted to articulate how that felt. For years we've been told that our stories aren't as important, that the concerns raised by Marian Keyes are lesser than those raised by Nick Hornby. I wanted to tell teenage girls that their stories aren't trivial. Their voices are worthy of being heard. I wanted to say 'speak up, you don't have to silence yourselves'."
Young adult gamechangers
Shadowshaper by Daniel Jose Older
Acclaimed fantasy writer Older makes his young adult fiction debut with this wonderful tale of Brooklyn teenager Sierra Santiago, whose summer is interrupted by magic and ghosts.
Am I Normal Yet? by Holly Bourne
An involving look at feminism, friendship and the secrets we hide even from those who know us best.
More Happy Than Not by Adam Silvera
Gut-wrenching story of race and sexuality set in the Bronx in the near future.
For Holly by Tanya Byrne
The latest from one of the genre's rising stars, a suspense-filled family drama with a gloriously angry teen at its heart.
Suicide Notes From Beautiful Girls by Lynn Weingarten
After her best friend kills herself, June tries to uncover the truth in this dark thriller that's been described as Gone Girl meets 13 Reasons Why.
Only Ever Yours (Quercus $24.99) is reissued on August 1.
- Canvas, Observer
