n 2005, at the Sundance Film Festival, a star was born, but almost no one noticed. Well, actually, a few studio executives who saw “Hard Candy” raved about the performance of the unknown Ellen Page — she played an avenging, psychopathic 14-year-old who entices and then violently tortures a would-be pedophile. But the movie was so relentlessly disturbing (at one point, Page’s character ties her enemy down and slowly begins to castrate him) that when “Hard Candy” was released the following year, no one went to see it. What the audience missed then is what they later found in “Juno” — the birth of a different sort of actress. Unlike her glamour-girl peers who double as tabloid superstars, Page, who is now 20, is a tomboy — her on-screen persona is sharp, clear-eyed, determined and self-consciously original. In “Hard Candy,” she managed to be adorable and persuasive while wielding a large knife; in 2007, that same spirit and charm animated “Juno,” a kind of fairy tale about a pregnant 16-year-old who decides to have the baby and give it to the couple (in the end, half the couple) she chooses. In “Juno,” the lack of realism — no one questions Juno’s decision — and the lack of politics are trumped by the overwhelming appeal of Page’s acting. She is so alive on screen — so unique, so ingratiating — that she makes the character, and the entire film, believable.
As is often the case with cinematic breakthroughs, Page had two of them: the first, “Hard Candy,” was her initial artistic birth; “Juno” then deftly married artistic cred with popular acclaim. Page is now a star. With breakthrough performances, as with almost everything else in life, context is everything. Diane Keaton was in three Woody Allen films before Allen wrote “Annie Hall” as a love letter to her quirks. Despite her brilliant comedic turns in the other films, “Annie Hall,” was, and is, the Keaton performance that cemented her cinematic identity. Just as Juno MacGuff probably has high-school girls trading their Uggs and belly-baring T-shirts for tartan plaid Converse sneakers and red hoodies, Annie Hall spawned legions of loyal followers. I, for one, started wearing a fedora and sewed copies of her outsize dresses. I think I may even have said “la-di-dah” once or twice.