“I began to tell him stories about this boy who was dyslexic and had ADHD, just like my son, only the reason why he had this is that he’s the son of a Greek god. My son loved this idea, and asked for the stories to be written down.”

Meet Percy Jackson, a teenager who discovers he’s a demi-god while fighting for his life against his malevolent Maths teacher. His creator, Rick Riordan, worked as a secondary-school teacher in Texas while pursuing a parallel career an award-winning author of hard-boiled detective fiction, and now finds himself poised to step into JK Rowling’s shoes. It wasn’t intentional, he says, though there are striking similarities between each series. Like Harry Potter, Percy is a disadvantaged teenager with special powers, who gains entry into a secret society of magical beings involving a special school; like Harry he has to stay alive despite the forces of evil for long enough to save the world. The difference is that Percy is American, and the world he encounters is that of myth, not fairy-tale.

“Very unsure” of what he was doing, Riordan sent Percy Jackson & the Lightning Thief off to a children’s agent, who accepted the book within a week. Within another week, a five-way auction was set up, with Miramax emerging as the winner in the US and Penguin buying it here. Twentieth Century Fox bought the film rights, and what had begun as a very personal story has now become a five-novel series, translated into 16 different languages. The third, Percy Jackson & the Titan’s Curse, is published this month.

I can’t think of a child of 10+ who would fail to enjoy Percy’s adventures, though not all the jokes travel equally well, and the slick style gives it a superficial gloss at odds with a deeper emotional content. Named after Perseus, the one Greek hero to enjoy a happy ending, Percy must avoid both the flaws of predecessors such as Jason and Hercules, and the monsters (ranging from Medusa to manticores) sent to destroy half-gods. Sent to Camp Half-Blood, the school where all children of gods and mortals can be trained to survive, Percy is soon on many quests. Together with his bumbling best friend Grover, a satyr, and Athene’s attractive daughter Annabeth, he first has to find Zeus’s stolen weapons of mass destruction and bring his beloved mother back from Hades; then save the immortals themselves from the “Great Stirring”. Though they share the same tropes as Harry Potter, these are distinctive, not derivative, works of fiction.

Percy inhabits a fully-imagined world, which, like Rowling’s, casts satirical reflections on its author’s native country. The Greek gods move Olympus to each dominant culture in turn – from Italy to England to America, as Zeus explains – and it is the witty fusion of the magical with the mundane which gives the series its edge. Centaurs wear T-shirts, Hermes appears as a FedEx mailman, a Monster Donut franchise really is a self-perpetuating monster, and Percy’s weapon is a ballpoint pen that expands into a sword. Little time is spent at lessons, though there are violent camp sports and a lot of rivalry between the children of different gods. Travelling from coast to coast, Percy and his friends experience their country’s materialistic crassness and its abiding nobility in equal proportion.

“America runs the risk of being a caricature of itself,” Riordan says, emphasising that when Ares, god of War remarks that “America is the best place since Sparta” it isn’t a compliment. However, “the idea of Western civilisation as a flame, and the burden and responsibility of that passing to America is also present. We may fail miserably, but that ideal is still there.” Indeed it is, and the gods living on the highest floor of the Empire State Building send our heroes help when they most need it – with gigantic bronze angels on the Hoover Dam coming to life and shielding Percy from terrifying skeletal warriors in The Titan’s Curse.

Like Philip Pullman and Eoin Colfer before him, success has meant that Riordan could give up teaching – but he did so with reluctance, once the demands of writing two novels a year became too much. He combined his career as an Edgar-winning “rock ‘em and sock ‘em” detective-novel writer with teaching because he loves schooling and always wanted to be the person in front of the blackboard. (Even his adult detective is an English college teacher.)

“I’m the son of two teachers, and I have a vocation to teach,” he says. The son of five generations of Irish immigrants, Riordan draws on fifteen years of teaching as well as his own experience of fatherhood to understand what modern schoolchildren encounter while growing up.

“I started in Texas state schools where most of the pupils were on free lunches as the only meal they got each day, their parents were on welfare and many were educationally challenged,” he says. “Then I taught for three years in a private school in California. But the problems poor children have and the problems of kids coming from much more affluent families are the same. They all need self-confidence, their parents’ attention, structure and boundaries.”

Percy’s journey, beginning as the child of a single mother with an abusive step-father, into genuine heroism, is drawn with conviction, as well as an ebullient sense of fun. Good-natured, humble and loyal, Percy’s affectionate nature, tentatively burgeoning into love now he has turned fourteen, is giving him a rocky time. In the real world however, Riordan’s son is now off his ADHD medication, “doing very well being home-schooled”, and as eager to read ten pages a day as his younger brother. With books as good as his father’s, you don’t need magic after all.

Ends.

Percy Jackson & the Titan’s Curse, by Rick Riodan (Puffin) is published this week.