As far back as Page can remember, she was a tomboy. She loved street hockey, Sega Genesis games, snowboarding and wrestling with her stepbrother. She wore her hair so short that people often called her ‘‘Allen.’’ At McDonald’s, when Page ordered a Happy Meal, she would always ask for the boy toy — the cashiers sometimes ignored her and gave her some kind of Barbie-style doll instead, whose hair she would immediately cut off. In her teens, she dated boys, but when she kissed them she felt nothing. It wasn’t until the end of high school, when Page finally kissed a girl, that she realized why humankind was obsessed with romance. She started dating other girls, but didn’t advertise the fact. She devoted herself to soccer, acting and schoolwork. In high school, she wrote a long paper about the absurdity of a binary gender system.

Page got her first big acting break when she was 10. A local actor named John Dunsworth was scouting Halifax’s elementary schools for talent. When he approached the drama coach of the Halifax Grammar School — a prestigious private institution on the south end of town — he heard about a remarkable little girl who had recently played the lead in the school’s production of ‘‘Charlie and the Chocolate Factory.’’ Dunsworth, who is now 69, still remembers the story: All the other kids brought their script to the first day of rehearsals, the drama coach told him, but this little girl left hers behind — she had memorized it. ‘‘So she was a committed little thing,’’ Dunsworth told me. This was the beginning of Page’s career: ‘‘Pit Pony,’’ a local TV movie about early-20th-century Nova Scotia mining life. (You can still find footage of the young Page on YouTube saying vaguely Canadian ‘‘abouts.’’) ‘‘Pit Pony’’ led to a whirlwind of local productions, which led eventually to bigger films, including the lead role in a movie called ‘‘Mouth to Mouth’’ — for which Page, at 16, playing a young anarchist, had to shave her head and travel to England, Germany and Portugal.

Acting was beginning to look like a viable lifelong pursuit, and so Page devoted herself to it completely; she decided to give up soccer and move to Toronto, more than a thousand miles from home, to attend a special program for kids with all-consuming careers: future Olympians, Drake. During this time, Page starred in a creepy indie film called ‘‘Hard Candy,’’ in which she played a teenager who traps and tortures a grown man stalking children in Internet chat rooms. It was the dark expression of the talent she would later show in ‘‘Juno’’: an innocent, seemingly vulnerable girl stepping into the world of adult sexuality — this time not quirkily, but with malevolence. That performance is what led Page to be cast, immediately after high school, in ‘‘X-Men: The Last Stand,’’ and not long after in ‘‘Juno.’’ Page wonders, sometimes, what kind of life she would be living if she had happened to be sick that day she was scouted at Halifax Grammar School. College, she thinks. Soccer.

Page doesn’t like to complain about the inconveniences of her glamorous fame. But that doesn’t change the fact that, at the height of her post-‘‘Juno’’ success, she was suffering. She felt thoroughly alienated — living in Los Angeles, far from home, famous almost overnight, and closeted. Instead of going on some kind of Angeleno child-star bender, Page removed herself: She traveled to rural Oregon to study permaculture at an eco-village called Lost Valley — a place that was not quite off the grid, but close. Residents slept in rustic dorms, with sheets hanging down as walls; they shoveled goat feces, trudged through mud and urinated in buckets.

At Lost Valley, Page met Ian Daniel, an affable, blue-eyed, red-bearded gay man from Indiana, five years older than Page, who had come to Oregon after traveling the country in a school bus powered by vegetable oil. Page recognized him immediately as a kindred spirit; she describes the moment he walked into her permaculture class as love at first sight. Daniel concurs. ‘‘We’re not lovers,’’ he told me. ‘‘We’re not in love. But it is kind of a love story.’’ When Daniel met Page, he hadn’t seen ‘‘Juno.’’ This made him the rare person who didn’t know the actress, first and foremost, as Juno MacGuff.

When he first saw Page, Daniel told me, he was ‘‘struck by how sort of average she was.’’ He had heard she was a movie star, but she was dressed ‘‘like any other young hippie on the commune’’ — jeans and hoodie. Something about her intrigued him, however. ‘‘She emanated this power,’’ he told me. It seems to have been something like the quality she showed at the Iowa State Fair: a quiet, focused, confident seriousness.

At Lost Valley, Page and Daniel talked about being gay in a predominantly straight culture, about the pressure Page felt at having to wear dresses and heels and hide her girlfriends from the press. Page returned to Hollywood after a month, and fell into a depression. Her role in “Inception”— in which she played a character named Ariadne, the architect of Leonardo DiCaprio’s convoluted action-adventure dream worlds — introduced her to a new audience, raising her profile and putting even more pressure on the fault line between public and private life. But her conversations with Daniel, among other friends, had helped sow the seeds of her future life: her public coming out, the fight for L.G.B.T. rights, the making of ‘‘Gaycation’’ (which Daniel would co-host) and ‘‘Freeheld,’’ the first film in which Page has played a gay character. At the Toronto film festival this year, she walked down the red carpet with her girlfriend, wearing a black suit.