Whole truth for teenagers: Patrick Ness's novels have attracted acclaim, awards - and censure

Patrick Ness has just won the CILIP Carnegie Medal, Britain's leading award for children's and young-adult fiction, for Monsters of Men: the third book of his acclaimed Chaos Walking trilogy. He speaks quietly, in a soft American voice; but he also speaks with passion, swiftly and with a habit of repeating words or phrases for emphasis. Some of that passion was vented at the awards ceremony, in which he deplored a government lamenting illiteracy while at the same time closing libraries.

You can't be a writer, Ness believes, without reading "hundreds and hundreds of books". As a child, he benefited from the freedom of libraries, where he was "always reaching for something too old". He does not believe in boundaries for books: he advocates reading everything, including trash, and thinks it is often enriching when one genre leaks into another – in Kate Atkinson's literary crime fiction, for instance. And he hopes in the future for leakage from the best of "young adult" fiction into adult fiction, notably its vibrancy and "robustness of narrative".

All three volumes of Ness's trilogy were shortlisted for the prize he has just won for the final book. The first, The Knife of Never Letting Go, also won the Booktrust Teenage Prize and the Guardian Fiction Prize, and the second, The Ask and the Answer, took the Costa Children's Book Award. The trilogy has variously been described as "too good for the young adult strapline" (a slur on YA) and "one of the most interesting fantasies ever published". Some have called it "dystopian" and even "sci fi" (Monsters of Men, publsihed by walker, was also shortlisted for the Arthur C Clarke award). While he "doesn't mind labels if they put books into people's hands," Ness feels, rightly, that these categories don't quite cover it.

Chaos Walking is set in the future, on another planet like our own, but where men and animals can hear one anotehr's thoughts (though dogs' reflections are limited). Women's thoughts are silent. It has, particularly in the first book, the atmosphere of a Western – a boy on horseback, a bad guy wanting small-town power – and it involves a love story, between teenagers Todd and Viola, and big themes including moral responsibility, attitudes to women, political deception and, notably in Monsters of Men, the nature of war.

A recent article in the Wall Street Journal caused a stir by asserting that "young adult fiction is rife with depravity". Ness has himself been accused, by the Daily Mail, of choosing subjects too dark for youngsters. Monsters of Men has a scene, for example, in which Viola is "waterboarded" under interrogation. But Ness thinks it is important to consider what teenagers write themselves: "I have judged teenage writing contests and it is extraordinarily dark material. Isn't it better to acknowledge that and say, 'All right, these are the things you think about, but let's look at them seriously, let's look at the real consequences and the real feelings that surround them'? To not write about serious things is, in a way, abandoning a young reader, and I just won't do that."

In fact, his books are questioning, and profoundly engaged with moral issues. One characteristic of Todd is his resistance to violence. "It was really important to me to consider what it means to kill. I do an exercise with my students [Ness teaches creative writing at Oxford University] where I make them imagine someone that they care about, and then make them write a scene of violence against that person. And it's awful. Why shouldn't all violence feel that painful, that powerful? Violence is often far too cheap in a book. Todd is a hero in a teen book so should be able to just swash-buckle, but he can't because I don't think in real life you could. I wanted the real truth of it, not even the literary truth, whatever that is."

Monsters of Men also explores, in a subtle to-and-fro that constantly undermines our allegiances and shakes our sympathies, how decent people can commit terrible acts. "Men do monstrous things but if you call a man a monster you have absolved yourself of blame. You don't have to think that you might ever do these things. I don't think that's true."

Although teenagers respond to the moral questions in his books, mostly they respond to the characters and the story. To Todd's dog, Manchee, whose sad fate, Ness admits, was sealed before he began the series. And to Todd and Viola, with both of whom Ness identifies. They are richly complicated. "I got tired of books where the boy is a bit thick and the girl's very clever. Why does it have to such an opposition? Why can't they be like the girls and boys that I know personally who are equally funny and equally cross? Who get things equally wrong and are equally brave? And make the same mistakes?"

Ness's own teenage years were spent in Washington State, and then in LA, where he studied literature at the University of Southern California. He now has British nationality; a photo on his often very funny blog shows him receiving it, and "accidentally looking like a fascist". Ness is 40, but he has a boyish face and demeanour, and you can still see the teenager in him.

He also has a very short haircut which would look fine on a GI. His father was a drill sergeant in the US Army, and his parents were evangelical Christians. This has led knee-jerk journalism to draw conclusions about Ness having a traumatic teenage, not least because he is gay (and now married). But Ness says this is reductive, and is very protective of his family. Although we can hear Biblical, sermonising rhythms in the rhetoric of his villainous politician, Mayor Prentiss, he insists that his father is "a very nice guy".

"Every teenager understands what it is like to feel that you are not understood. To be given rules that seem unfair that have no justification other than 'I am older than you; I am telling you what to do'. I lived in a world of certainties that were not going to agree with me. But that is basically a description of what it means to be a teenager."

Ness is surprised when people can't remember their own teenage. "I remember the good times, the laughs with friends, all the goofy stuff, all the stuff you got away with, but I also remember difficult times – figuring out where friendship is, figuring out dynamics with other people, what real starting-out adult relationships are like. You have a lot of the responsibilities of being adult with very few of the privileges so there is this ongoing sense of injustice."

Literature influences Ness's writing as much as memory does. His first books were for adults: a novel, The Crash of Hennington, and a collection of short stories: Topics About Which I Know Nothing. He confesses that he reads more adult than YA fiction and admires authors who make him feel that their story is a fragment of a much larger world – Peter Carey, Nicola Barker, Ali Smith. He also enthuses about Mal Peet's supposedly YA book, Life: an Exploded Diagram, which has "everything I want in an author. I want them to be strong and to lead me somewhere surprising."

Chaos Walking is told in first-person narratives, in the voices of Todd, Viola and, in Monsters of Men, a third character belonging to the demonised and enslaved Spackle race. Todd's voice grew out of Ness's admiration for Russell Hoban's post-apocalypse novel Riddley Walker, "one of the most extraordinary books of the last 50 years". He has taught it, and was one of many writers – he cites Will Self and David Mitchell in Cloud Atlas - who "have thought 'I'll have a go at that'. But as I wrote the voice it got simpler and simpler and simpler. And by then it revealed itself as a YA thing, and Todd was a teenager with YA issues."

One of these issues is privacy, a theme of the book, which Ness reflects on in the light of super-injunctions and our culture of constant communication. "We have lost the idea that something can be secret because it is valuable, not because it's shameful. If you share everything with everybody, what have you got for yourself? I tweet and I blog but I save a lot for myself. Not because I am ashamed."

Ness also much admired the late Siobhan Dowd, who was on CILIP Carnegie shortlists with him. (She won the Medal, posthumously, for Bog Child.) Since Monsters of Men, Ness was commissioned to complete a book of hers, for which she had left a premise, a bit of prose, the characters, and an enthusiastic email to him full of the joy of telling the story and "ideas that were so vivid and so potent and so full of life that they immediately started other ideas". Ness ran with the ball (he has written to a commission before as a Booktrust writer in residence) but wrote not an imitation of Dowd but a tale in his own style. A Monster Calls (Walker) is now published, and concerns a boy whose mother is dying of cancer - as Dowd did - who is visited by a storytelling monster who helps him come to terms with his emotions.

"What is important me in the Chaos Walking books and is the whole point of A Monster Calls is the complexity of a person. That you are at one time many contradictory things. That a terrible thought doesn't make you a terrible person. That a mistake is natural and human even though everybody blames you for it. You are going to mess up but that is not the point; the point is how you react to it, how you fix it, how you grow from it."

Teenagers, Ness believes, are just the audience for this, because "Your reader is interested in a guileless, fresh, first-time-we-talked-about-it way. What a great liberation that is. And teenagers, if you respect them, will follow you a lot further than adults will, without fear of being a genre that they may not like or have been told not to like. They just want a story."