– STEVEN ZEITCHIK

McClatchey Newspapers

LOS ANGELES – There are many holy grails in Hollywood, but few as pursued as the slow-burn success — that film that doesn’t blow away audiences when it first comes out but hangs on long enough to become a breakout. Like the Holy Grail, the slow-burn is frequently sought (well, by movies that don’t blow away filmgoers when they first come out). And like the Holy Grail, some wonder if it even exists.

These kinds of hits certainly occur with far less frequency than they did five or 10 years ago. And these movies rarely hang in for very long. Even the slow-burns burn faster than they used to.

Twelve years ago, for example, saw “There’s Something About Mary” muck around between the second and fourth spots on the weekend box-office charts for nearly two months before finally breaking through and hitting No. 1. (The movie went on to gross $176 million, good enough for the third-highest total of the year.) “Avatar” made some strides in this direction; while the movie followed a more traditional trajectory of a solid month at No 1. before falling from the perch, it was able to show week-to-week gains in ticket receipts even several months into its release.

And then, of course, there’s the exemplar of the form: “My Big Fat Greek Wedding,” which actually never hit No. 1 over its remarkable run in 2002 and 2003. In fact, the film took four months even to expand beyond 750 screens. But despite a quiet rollout, the movie continued to amp up the decibel level, as, every few weeks, new waves of people seemed to discover it. the time its run ended, the film had played in theaters for nearly an entire year — a century in box-office time — and had grossed an astonishing $241 million, ahead of blockbusters such as “War of the Worlds” and “The Bourne Ultimatum.”

This year’s candidate for the slow-burn, “How to Train Your Dragon,” isn’t likely to hang around for 12 months, or even until August. But there’s something “Greek Wedding”-like about it just the same. When it opened last month, the movie debuted at No. 1, but with a soft-ish $43 million. Then it fell from the top spot, vacillating between second and third place for the following three weeks. And this week it reclaimed it.

There are plenty of distinctions between “Dragon” and the previous slow-burns. The animated tale has hung on, but that hanging on is measured in smaller drops, not renewed momentum — unlike “Wedding” or “Mary,” it hasn’t gained audience week-to-week.

And of course both those examples played through the much busier summer period, not the box-office doldrums of the early spring. But it’s still a remarkable feat. Most movies, especially animated ones, will never get back to the top spot once they’ve fallen from it. (“Wall-E,” an equally well-reviewed and well-received animated film, fell out of No. 1 and never climbed back; by its fifth week it was in seventh place, grossing less than half of the $15 million “Dragon” did in its own fifth week.)

So what is it that keeps a movie like this going? Obviously it’s about good word-of-mouth, but that’s like saying a good restaurant is about tasty dishes. We’d offer that it’s about subtle charms, the kind that reveal themselves over time, and get people to see it who never thought they would. “Wall-E,” as strong as it was, made its virtues known pretty much right away: a cute robot in outer space. What’s not to like?

“Dragon” isn’t as immediately inviting. The title tells you nothing (and in fact gives off the faint whiff of an instructional video). And a dragon is hardly a cuddly animal. But as filmgoers discover it, they give the DreamWorks Animation film momentum beyond any point when it reasonably should have.

For the most part, box office is still a combustible firecracker more than a gentle flame. But even in these times, it’s nice to see a movie burn slowly. At least until a movie like “Iron Man 2” extinguishes it in a couple of weeks.