Oct. 1, 2010 -- "Let Me In," the highly anticipated vampire-themed movie opening today, tells the story of two pre-adolescent misfits. The downside: She's a vampire. As the saying goes, young love is never easy.
Although the film's message -- making peace with one's outsider status is much easier to do with the support of a friend -- is sweet one, "Let Me In" is, in parts, bloody, gruesome and graphically violent.
So when a movie so fearlessly explores the dark side, what are the ramifications for the child actors who are part of that journey?
Chloe Grace Moretz, 13, plays Abby, who describes herself as someone who's been 12 for a very long time. Her vampire genes require regular feeding, and she's not shy about licking blood off the floor and giving herself a bright-red smeared pout that's not from lipstick.
Kodi Smit-McPhee,14, plays Owen, a profoundly lonely, graphically bullied-at-school child of a single mom. He quickly figures out that Abby's blood-soaked beauty -- and hearty appetite -- has considerable and possibly insurmountable challenges.
The subject matter prompts the question: Were any children harmed in the making of this movie?
"Much depends on the child's acting teacher or coach, as well as the director's level of support on the set," said Lynette McNeill, an acting teacher, coach and consultant, and owner of Lynette McNeill Studio in Los Angeles.
In Overture Films' production notes for "Let Me In," Smit-McPhee talks about the advice he received from his father, who's been an actor for 20 years.
"My dad taught me that for simple scenes I can just turn it on and off, but when I'm doing the really intense scenes, I have to stay in that character all day," he said. "I can't muck around. It's a really emotional movie, especially for Owen. There were some days that were really fun, and other days that were a lot harder."
Most recently, Smit-McPhee co-starred, with Viggo Mortensen, in the grimly apocalyptic "The Road."
Moretz is no stranger to playing unsavory characters, having portrayed a mini-assassin in this year's "Kick-Ass."
How do all child actors cope with these types of roles or serious subject matter?
"Ideally, child actors are taught to create their characters truthfully from their imagination," said McNeill. "We emphasize to the children that they imagine these things, because keeping it in the realm of imagination is what helps separate reality from acting.
"If, however, to get a better performance, a teacher asks a child actor, 'Have you ever wanted to hurt someone?' -- in effect, suggesting that the child merge with his character -- then the teacher may stir up something emotionally and thereby cross the line."
McNeill described a danger sign.
"If child actors are so wrapped up in the part that they can't separate themselves from the part at the end of the day, then they're still in that role, which is not a good thing," she said.
Separating from the role is sometimes challenging, because the child has just received praise for his or her creativity and doing a great acting job.
"This combination can be intoxicating," said McNeill.
One remedy, she suggested, is to ask the child, "Are we done here?"
"I always tell my actors not to keep replaying a scene," she said. "If the child is reluctant to be done with that part -- if he or she goes on a little too long -- it's important to remind the child to end on the scene and go back to being himself."
"A lot depends on whether the child is able to handle the script and to understand whether it's make-believe," said John Northman, a clinical psychologist in private practice, in Buffalo, N.Y. "It's important that a child not internalize the role by making that role part of himself."
Rudy Nydegger, a clinical psychologist with an expertise in child and adolescent psychology in Schenectady, N.Y., and professor of psychology and management at Union Graduate College, noted that on a film set the action is filmed in pieces, and the child actors tend to be professionals.
But damage could occur when non-professional child actors -- real kids -- make a movie on their own, he said. In the backyard, kids must create in that setting, often for longer stretches of time.
"They're not professionally trained to turn it on and off," he said. "The context is different. It's a lot more real in the backyard."
Lindsay Frame, an acting teacher at Anthony Meindl's Actor's Workshop in Hollywood, said, "Generally, by the age of 12, children who attend our school have a sense of their own boundaries when it comes to working with sexual content, swearing, or the like.
"Anthony and I have met the parents of our young students. And by the time the children start classes, they've already established a code of personal boundaries, with the help of the parent or parents, that they're comfortable with."
During classes, Frame checks in frequently with the children's comfort level, especially when students aged 12 or older are working with more adult-related content.
"If they're not comfortable, we allow them to sit out parts of the class," she said. "Open communication is very important."
Ultimately, it's the parents' responsibility to make sure what happens on a movie set has no deleterious effect on the child.
"The parent is accountable for finding out exactly what the part entails, asking the director how sensitive scenes will be shot, and letting the appropriate people know that a parent will be sitting in on the set," said McNeill. "Good directors are going to be looking out for these things, but parents should never make assumptions."