''I started working on the books in 2005,'' he says from Houston, Texas, where he is professor of English at Rice University. ''The little boomlet that we've experienced - well not so little actually - hadn't started.''

At 50 he may now be a best-selling dystopic novelist, but Cronin still takes an academic view of the rise of vampires as well as of the genre's current flagship. ''Everyone asks 'Have you read Twilight?' '' he sighs. ''The answer's no, I'm not the demographic. I drove a car pool of seven teenage girls, I know all about it that I need to know.''

He dismisses suggestions that the recent success of authors such as Stephenie Meyer is anything new. ''They talk about 'vampires are suddenly hot','' he says, sparking to what feels like a passionate cause. ''Vampires have always been hot. They are one of our most durable monsters. It's one of those stories that galvanises us early and it's always going on.''

Despite his success, Cronin is averse to use of the word vampire, referring to those in his novels with many terms - mostly as ''virals'' - but seldom using the v-word. He is however well versed in the history of vampire story telling. ''It has the most interesting lore,'' he says, comparing the genre to tales of werewolves and zombies that he feels ''are simple by comparison''.

''This legend is so common it seems to have arisen on its own in many cultures in the world. Our vampire myth is mostly an eastern European village myth, but you see versions of it everywhere.''

The global nature of the legend forms the premise of his series, though in the books it is a team of scientists backed by the military, not tweed-wearing literary professors, who go in search of the ancient virus that mutated people into beings resembling our concept of vampires. The results are a genocidal army of afflicted humans with a very familiar set of attributes. ''What I wanted to do was to write vampires without magic,'' he explains. ''The traditional gothic vampire is a magical creature. It has many attributes that do not correspond to any physical or biological attribute I'm acquainted with; everything that has molecules will be reflected in a mirror, people can't fly. So what I wanted to do, the supposition of the book, is that there's some substance to it. Where does this really come from? So what these scientists do, they go looking for what they believe to be a virus that reproduces symptoms that over time have become the legend. In other words, the real vampires, where it all really started.''

The result to date is two epic instalments for a trilogy that are as thoughtful about human nature as its author is about the genre he is working near, if not exactly within - for Cronin is compared to Cormac McCarthy as often as Stephen King. As a student of literature, he is flattered by such comments and deeply respectful of his forbears.

''As a writer, I didn't invent the novel,'' he says. ''It was invented for me and thank god somebody else did it. So whenever I'm writing, I'm writing in the presence of all the other books I've read and I think we all are. As writers, we're always in the presence of a whole wall of books, a whole library of books, so rather than pretend that it isn't true, I just kind of throw my arms around it and make use of it in the books.

''Everywhere in both of these novels there are an assortment of winks and nods not just to the vampire legends and vampire stories - the original Dracula, the movie Dracula - but also lots of literary traditions and particular books that taught me how to write. There's a whole extra layer of literary acknowledgment that goes on in these novels which frankly readers don't have to notice if they don't want to. It's sort of like an Easter egg hunt for people who want to go do it.

His love of a literary reference informed his decision to locate at least some of the action in Australia, with parts of the first two books presented as extracts from a seminar a thousand years from now held at the University of NSW.

''What makes this a horror novel, a thousand years in the future there will still be academic conferences,'' he jokes. ''I wanted to use Australia and New Zealand in the novels for two reasons. One, I've just always wanted to go there. I'm hoping my publisher will send me there and I'm very excited.

''It's also a literary reference. It's a reference to a novel that made a big difference to me, an apocalyptic novel called On the Beach by Nevil Shute. If you know the novel, you know it's all set in Australia while a group of survivors wait for a cloud of radioactivity from a global nuclear conflict to come and kill them all. And that's an important book not just to me, but in the history of the way people thought about global nuclear conflict. I'm acknowledging a debt. To a book that wasn't just important to me but important to the world.''

So will we learn how an Australian university winds up hosting a conference a millennium from now into events in a post-apocalyptic North America? ''Well if I told you that I'd be giving away waaay too much,'' he says and laughs. ''Based on those documents I think you can feel assured that your world will feature prominently in the story.''

Such revelations will only appear in the third instalment of the series, The City of Mirrors, due for release next year. For now fans are left to pour over the second instalment, The Twelve, a book that jumps back in time in the story.

''When I wrote the second book I decided that I would not simply continue the story of the first book. I mean obviously I do, but by going back into the past I was able to in a sense change the stakes of the story. In the second novel, in the beginning, you go back to see events from the world of the first book that you didn't see directly or that you only glimpsed out of the corner of your eye.''

Even when discussing the plot of his own novel, the academic's brain carefully references his sources. ''One of the things is that you don't really leave anything behind,'' he explains. ''As William Faulkner says: the past isn't even past. These three contexts, these three time periods that the novel avails itself of, they are all really of a piece.

''I wanted each of the books to set their own terms. I think that's the problem of second books in a trilogy or triptychs, that the second book is kind of a bridge between books one and three it just continues the story to get you to a later conclusion. I needed to have something that would turn the plot. Make a hard left or hard right and that again was an interesting challenge for me and I really wanted to do it.''

Another challenge for Cronin came in the form of the first book's fans, whom he interacts with online and who have changed his view on his own novel. ''It fascinates me,'' he admits. ''It gives me a very intimate look into people's experience of the novel. I just opened my Facebook fan page to answer some questions, I do it all the time. It's very satisfying and sometimes it changes my view of what I think the books need to be. Once in a while someone asks a question and I think that's a really good question, I've got to deal with that question.''

It's surprising for an author to admit he changes his own novel based on the readers, that such a well planned series can be so fluid. ''I always say it's sort of like jazz,'' Cronin says. ''There's a strong melody in there somewhere but once in a while, it's under there and you can feel it, but sometimes you're riffing off of it. There's an outline for each of the books that I adhere to pretty closely, but I'm not averse to taking it in a new direction as long as I can get it back to where I need it to go.''

Cronin is also very relaxed about the movies that are already being planned for his trilogy, and the changes that will be inherent in the process.

''I leave this to the experts. I'm not an expert. I've never written a movie, I'm not in the movie business, I go out to LA and I'm like everyone else wandering around in a daze hoping I see movie stars. I write the novels that the movies are based on and that feels like enough of a job for me.''