SO, you're just eighteen years old and you've been working in Hollywood since you were six. You've already worked with Steven Spielberg, Tom Cruise, Sean Penn, Robert De Niro, Denzel Washington, Julia Roberts, Kurt Russell and countless other A-list names.
"Of course, everyone knows where the story is going so you also have to make every moment of the film matter. It's emotional and painful but also really beautiful."
You're also part of the hugely successful Twilight franchise and you were the youngest person ever to be invited to join the Oscar-voting Academy. What's the obvious next step?
Yes, that's right, come to England - Brighton to be precise - to star in a low-budget British movie as a teenager who's dying of leukaemia.
But then, Dakota Fanning isn't just any other Hollywood brat and Now Is Good isn't just any other 'disease of the week' story.
Written and directed by Ol Parker (writer of The Best Exotic Marigold Hotel), based on the novel Before I Die by Jenny Downham, Now Is Good pulls off the rare trick of being moving without being sentimental as it tells the story of 17 year-old Tessa (Dakota Fanning) and her decision to live her life to the fullest after receiving a terminal diagnosis. Writing herself a sort of ‘bucket list’ of things to do before she dies, Tessa goes through a host of new experiences, including falling in love.
Ol Parker with Dakota Fanning at The Printworks premiere
There's also a top-notch British cast, including Paddy Considine in the key role of Tessa's over-involved dad and Olivia Williams as the pleasingly feckless mum, with The War Horse's Jeremy Irvine as, quite literally, the hunk-next-door.
Dakota is the sort of star who (over her own protests, it should be pointed out) really did need security to help her get in and out of last week's Odeon, Printworks preview screening. She clearly doesn't need the profile or the credibility. So why would she, as Ol had already told me, have so actively pursued the role of Tessa?
"I just loved the story and loved the character, plus when I met Ol I just immediately wanted to do it. I hadn't read the book, no, or even heard of it. I still haven't, in fact, but I did meet Jenny while we were filming and she seemed happy.
"The challenge of the story and the character was trying to make every moment matter. Of course, everyone knows where the story is going so you also have to make every moment of the film matter. It's emotional and painful but also really beautiful.
"There are things that she sets out to do, but I think a theme of the film is that life just happens. You try to plan things, but sometimes you have no control, and that can actually be pretty great."
"Amazingly she did chase it," confirms Ol. "She loved it and that meant a lot, although you don't just cast someone because you're flattered. But when she wants something, she's extraordinary. She'd read it and I don't know how she got hold of it because we didn't send it to her. But there was something in her determination to get the part that did seem to match Tessa's drive.
"Once we'd met she didn't have to chase anymore but she was the one who prompted that initial meeting. I was in LA at the time with my wife (actress Thandie Newton) when I got the call from her people. So I went to see her in some hotel and she'd got the part before the tea had arrived."
But maybe playing an ordinary teenager, albeit with all the usual teenage stuff complicated by impending death, isn't so unlikely after all. Part of Fanning's appeal in person is her remarkable ability to seem so, well, ordinary and she seems genuinely taken aback when I suggest, as hundreds of journalists must surely have done before, that spending most of your life so far on film sets is actually rather extraordinary.
"It's just what I do, it really is. Everyday life is oddly similar to everyone else's, it really is," she insists. "This has just been a part of my life like a sport might be part of someone else's life. You grow up and you practice hours and hours a day, then you go away for your competitions or your games. When you think about that, it feels like it's on a different scale but it's really, really not. This has just been my extracurricular activity in my life and it's become my career and what I want to do in the future."
That's an interesting analogy to draw, given that both Fanning's parents have been professional athletes.
"My mom played tennis for six hours a day and went to college on a tennis scholarship, because that was the way she could go to school," she recalls. "So they instilled in me the idea that you have to work hard for the things you want in life and never complain. I’m very grateful for that."
Although she's reluctant to personalise these things too much - acting is after all "an extracurricular activity" - she admits at the post-screening Q and A session at The Printworks that part of what drew her to the story was also that "as a young woman you have dreams of having boyfriends, going to college, meeting someone you want to spend the rest of your life with and having kids. So thinking about someone for whom none of these things will happen, that was what took me there.
"Yet, ironically enough, this was one of the most fun times I ever had making a movie. I just enjoyed everyone's company so much."
She did attend high school, where she was even a cheerleader and she's also currently studying at New York University. Isn't that, at the very least, a bit of a logistical inconvenience, given that she has more film credits than she's had birthdays?
"It would seem that way but that's just normal to me. I've been working since I was six and, obviously, going to school since I was six. I went to a regular, whatever that means, high school and didn't have home schooling or anything like that because I wanted the social part of it and the classroom experience. When it comes to going to college, I don't have a major yet, and I don't have to decide for a while so I can just do what I'm interested in. I'm taking classes from British Victorian Literature to a class on Mythical Monsters. Being a part of the Twilight franchise is useful for that one.
"Funnily enough," she muses, "I don't get recognised so much from Twilight because I'm in it so little and look so different but being recognised has been a part of my life for a long time."
Next month she's off to Oregon to start filming opposite Jesse Eisenberg and Peter Sarsgaard as an eco-terrorist in Kelly Reichardt's Night Moves.
"No relation to the Gene Hackman film, although that would be weird and cool," she laughs.
But perhaps more significant in the way this remarkably self-possessed young actress might yet develop, is the other film she shot in the UK last year. In the soon to be released Effie, she stars as the teenage bride of the Victorian art critic John Ruskin.
It's directed by Emma Thompson, of whom Fanning enthuses "She is such an amazing woman and writer and actor and humanitarian and mother and wife. She just has it all down.
"I want to be like her when I grow up but, for now, I'm taking my time."
