Vampires are everywhere these days. There are the Romeo and Juliet-style stories of Twilight and the steamier True Blood as well as the love triangle of the CW’s Vampire Diaries. And now there is “Cirque Du Freak,” based on the best-selling series of YA novels by Darren Shan, who shares his name with the title character.

I think it is because in this open-minded and permissive era it is hard to find a reason to keep an ordinary romantic couple apart. In the old days, parental disapproval, not having enough money, or societies’ strictures could fuel an entire movie until the happily-ever after ending. But these days it is difficult to create narrative tension to keep a couple separate for 10 minutes, much less two hours. That may be great for society, but it is tough on story-tellers. And so in order to get transgressive, a bit of cross-species romance seasoned with the risk of death and the prospect of an unleashed id can make a story very captivating.

Teenager Darren Shan (Chris Massoglia) feels that his life is just fine. He gets good grades. Kids at school like him. His parents are proud of him. He has a life-long best friend named Steve (Josh Hutcherson of “Bridge to Terabithia”), who is restless and unhappy.

Darren does not want to admit that he also has his restless moments and is not always comfortable being what Steve calls “perfect boy.” Darren wants to make sure we understand that he is no longer close to a former friend who has become “a freak,” meaning that he does not dress like an ad for a soft drink. He is not sure that he will be satisfied with what his parents tell him is “the path to a happy, productive life: College! Job! Family! And one day, if you’re lucky, you’ll be yelling at a teenager of your own.”

And there’s Darren’s lifelong fascination with spiders, not studying them, more communing with them. Steve is obsessed with vampires and dreams of becoming one himself. They pick up a mysterious flier about a freak show and sneak out to see it. When Darren steals a poisonous spider and it bites Steve, Darren agrees to give up his life as a human to become the vampire’s assistant in exchange for the antidote.

It makes some changes to the story in the book series but it is true to the tone — a nice combination of teenage angst and outrageous grotesquery, with the implicit recognition that sometimes it can be hard to tell the difference. Massoglia and Hutcherson come across as bland at times, but then they are sharing the screen with a snake-boy and a lady who not only has a beard but is the mesmerizing Salma Hayek. The story can be exposition-heavy as it lays the foundation for the next episodes in the series by starting up a war between two vampire factions. But it benefits from small details around the edges that attest to the fully-realized world of the novels. It balances the scary moments with humor. And it has good guy and bad guy vampires, a rock music-loving snake boy (Patrick Fugit, one of the film’s highlights), a woman whose limbs regenerate, a super-tall guy who kind of looks like Edgar Allen Poe, and a world of freaks that knows how to make the Cirque feel like home.