Philadelphia ? “There are few things that couldn’t be improved by adding vampires to them,” Scott Westerfeld says.

His new book, “The Last Days,” is certainly vampire-enhanced. Set in a spooky modern-day Manhattan, it tells a story as old as time: five kids form a band, wanting only to become rock stars before the apocalypse arrives.

“The Last Days” couldn’t be described as a typical Westerfeld novel, because there is no such thing. The fiction of this 43-year-old Texas native is as mercurial as the teenagers he writes it for.

His best-known work, the Uglies trilogy, concerns a futuristic society in which cosmetic surgery is mandatory for all adolescents.

He has started a new trilogy set in a reimagined version of 1914 with very different technology. “I happen to be one of those zeppelin geeks,” he explains. “And to write about airships in a way that matters, you have to write an alternate history.”

A reformed science-fiction writer, Westerfeld has a free-range imagination. But his novels share certain characteristics.

“Scott’s books are so brilliantly plotted, and you care about the characters so much, that you’re compelled to keep reading,” says John Green, who won the prestigious Printz Award this year for literary excellence in young-adult literature for his novel “Looking for Alaska.”

“I stayed up long past my bedtime reading ‘Peeps,”‘ the 2005 predecessor to “The Last Days,” Green says by e-mail. “But what’s impressive about his writing, to me, is the way that he explores both contemporary problems and the existential problems that are central to the human experience.”

Classroom antics

Westerfeld prefers writing for youngsters because of their visceral honesty and lack of pretension. “I think teens are more demanding readers,” he says. “They don’t allow a lot of self-indulgence. They’re not into a character standing and looking at a dishrag thinking about how the dishrag is like their life. It’s more about old-fashioned storytelling.

Scott Westerfeld's latest book, The

“I think that’s why a lot of adults read YA fiction,” says the writer, who splits his time between New York and Sydney, Australia. “The modern novel doesn’t have that much to offer them.”

Younger readers also have more linguistic flair. “A high percentage of teens are writing poetry and using nicknames and memorizing song lyrics and learning languages,” Westerfeld says. “So you can play a lot more in teen fiction with inventing language.”

Westerfeld cobbled together the striking futuristic slang in the Uglies trilogy from Australian idiomatic expressions and flappers’ argot from the 1920s that he borrowed from Evelyn Waugh.

Another advantage of writing for teens: It’s the most generous genre left in the increasingly cutthroat world of publishing.

“Adult literary novels go on the Barnes & Noble shelves for six weeks and if they don’t sell, they disappear,” Westerfeld says. “But in the world of kids’ books, there’s more time for word-of-mouth to spread.

“There are a lot more champions for YA fiction, like teachers and librarians,” he says. “All those little bookstores that disappeared in the Barnes & Noble world? They still exist. They’re called classrooms.”

New kid in town

As an early techno-brat, Westerfeld saw far more classrooms than your average kid. His family moved often because his father was an in-demand computer expert. “He worked for Univac back in the days when a computer came with a bunch of guys in suits,” Westerfeld notes.

At his Dallas high school and later at Vassar College, in New York, Westerfeld was a promising composer. He says he turned down a scholarship to Julliard to pursue a graduate degree at NYU, but left before finishing his master’s thesis on Japanese all-girl garage bands.

For the next seven years, he worked in publishing in Manhattan, leaving in 1995 to see whether he could make a living as a writer. He supplemented his meager income as a sci-fi novelist with ghostwriting, including five Goosebumps books under the R.L. Stine franchise, and a legal thriller credited to a famous trial attorney Westerfeld will not identify.

In 2002, shortly after marrying Justine Larbalestier, a historian of science fiction, and moving to her native Australia, Westerfeld was contacted by a friend who worked for Fox Family (now the ABC Family Channel). She asked whether Scott had any ideas for a children’s show with a supernatural “X-Files” vibe.

His proposal about the strange goings-on in the town of Bixby, Okla., never made it to television. But Westerfeld became intrigued with developing it into a novel.

“I was in Sydney, a new city, in a new marriage, and working on a new kind of book,” he says. “So it starts with a new kid arriving in town.” Thus was born the Midnighter series and a new career path for Westerfeld.

“One of the things that makes science fiction and YA writing similar is that they both start with the idea that the world doesn’t have to be the way that it is,” he says. “As an adult, you get used to a lot of stuff. But younger people tend to be more idealistic. They’re not used to the idea that there are rich people and poor people.”

Outsider life

Shuttling between New York and Sydney was originally a way to escape winter’s clutches. But the peripatetic lifestyle also feeds Westerfeld’s writing. “You always feel a little alienated from the places you live, like an outsider,” he says.

“But you’re always behind on the movies and the latest catchphrases. I came back to New York after spending all of 2002 in Australia and everyone was saying, ‘You’re fired!’ ‘You’re fired!’ I was like, ‘What is that?’ “

Ask any teen: Some things, you’re better off not knowing.