Ten screenplays will compete for two awards tonight at the Oscars, and they couldn't be more different.

Ten screenplays will compete for two awards tonight at the Oscars, and they couldn't be more different.

"That's what is so amazing about this year," says Ronald Harwood, nominated for adapting "The Diving Bell and the Butterfly." "It's so diverse."

Front-runners have emerged in both the original and adapted categories, but they are by no means guaranteed to win.

In the original screenplay category, the nominees are "Juno" (written by Diablo Cody), "The Savages" (Tamara Jenkins), "Lars and the Real Girl" (Nancy Oliver), "Michael Clayton" (Tony Gilroy) and "Ratatouille" (with a screenplay by Corvallis High School graduate Brad Bird, from a story by Jan Pinkava, Jim Capobianco and Bird).

"Juno" appears to lead the pack. The comedy has won a host of awards for first-time screenwriter Cody, including honors from the Writers Guild of America. "Juno's" front-runner status marks a remarkable coming-of-age for Cody, the one-time stripper who admits she didn't have a clue how to write a screenplay.

Like "Juno," Oliver's "Lars" is a comedy-drama that centers on a quirky, off-center character. A writer on HBO's "Six Feet Under," Oliver came up with the idea while working for a company through which she discovered a Web site devoted to selling ultrarealistic synthetic dolls.

Turning her discovery into a full-length screenplay, however, meant forgetting the gimmicky aspect and exploring what kind of person would fall in love with a doll. And that meant centering on issues of loneliness that she says have interested her.

"The reasons why he fell for her are completely in there; all the reasons why he meets her unfold," she says.

"Ratatouille," the only animated film nominated and, along with "Lars" and "Juno," is arguably one of the very few to take a brighter view of life.

"The first thing I did was try to keep all the character types intact," Bird recalls about joining the production after it began, "and very quickly I came to the conclusion that there were too many possible stories, and I had to throw some overboard. But in doing that I found things that ended up becoming very important to the film.

"My way into the story was to connect with the rat who aspired to higher things," he says. But that did not mean he focused on craft at the expense of theme. "The challenge was to do that all in a way that felt natural and effortless, joyfully, without the heaviness that often comes when you try to write about things that are important to you."

Jenkins tried to avoid some of that heaviness in "The Savages," her mordantly funny tale of siblings coping with their father's dementia. Jenkins traces her story's roots to her own father's illness. "Obviously, you tend to write characters that you identify with," she says.

More popular is "Michael Clayton," a movie Gilroy spent years fighting to direct.

"It was flirting at the margins of commerce and art," he says of the thriller about a lawyer who uncovers corruption at the heart of an agrichemical company his firm represents.

If "Juno" and "Lars" split the quirky-screenplay vote, "Clayton" could be in with a chance of winning the original screenplay Oscar. But the Academy has generally steered away from straightforward thrillers in its writing awards.

Among the adapted screenplays, WGA winner "No Country" is the front-runner and will compete with "Atonement" (adapted by Christopher Hampton from Ian McEwan's novel), "Away From Her" (adapted by Sarah Polley from Alice Munro's story "The Bear Came Over the Mountain"), "The Diving Bell and the Butterfly" (adapted by Harwood from Jean-Dominique Bauby's memoir) and "There Will Be Blood" (adapted by Paul Thomas Anderson from Upton Sinclair's novel "Oil!").

"No Country" is the first adaptation brothers Joel and Ethan Coen have directed, though they have adapted other novels as writers-for-hire, including Elmore Leonard's "Cuba Libre." Longtime fans of Cormac McCarthy, they had not been tempted to film his other novels, which seemed to lack the inherent movielike structure of "No Country."

The movie's ending has divided even admirers of the film. But the brothers insist they never thought of changing it, even though that meant killing off a leading character and leaving the story hanging on a note of ambiguity.

"We were certainly aware, going in, that it was an unconventional shape to the story," says Ethan Coen. "We thought about it, given that it is not the usual (ending). You are aware that it is going to frustrate somebody. But it is faithful to the book in that respect, and that is what we liked about the book."

If "No Country" is the front-runner, it is by no means a lock. "Atonement" is also in contention. Hampton — like the Coens ("Fargo") and Harwood ("The Pianist") — is a previous Oscar winner in the screenwriting arena for 1988's "Dangerous Liaisons." Hampton has been praised for rendering a highly literary novel in cinematic terms, but the final screenplay was significantly different from his initial version.

"Various different solutions suggested themselves," he acknowledges. "But my instinct was to be as faithful to the book as possible."

"There Will Be Blood" is another period piece, but an American one, and its boldness has impressed many Academy voters. In adapting a part of Sinclair's 1927 tome, Anderson wrote what is in many ways more of an original screenplay than an adaptation, reinventing the lead character, an oilman played by Daniel Day-Lewis, and disposing of most of the story.

"The main thrust of what we took from the book was the buying of the town," Anderson explains. "We decided that was a more manageable approach to what could be shot (and made into a film of) under two and a half hours."

But "Blood" is dark and — well, bloody. And the Academy might find its bleakness too unpalatable for an Oscar.

That bleakness could have defined "Diving Bell," but Harwood took pains to avoid it.

"There were two things that were critically important," he says. First was his decision to have the camera's viewpoint and his hero's be one and the same, certainly at the beginning of the movie, when we see the camera "blink" as if we were looking out of his paralyzed hero's eyes.

The second important decision Harwood made was to avoid showing too much of Bauby in his debilitated state.

"There was that thing of not wanting to look at him for two hours in a terrible life state," he says. "And that was the real sticking point until I came up with my solution" — to have the camera show Bauby's point of view.

"Away From Her," the remaining nominee, was an unexpected finalist. Close as it hews to Alice Munro's story, the Canadian movie — which deals with dementia, like "The Savages" — presented its own challenges.

"There is so much that happens that is interior," Polley says. "For me, it was about finding ways of making the characters' inner lives accessible to people without making it too literal. There were scenes where Alice Munro says things about the characters that ended up being part of the dialogue."

It was the characters themselves that fascinated Polley. And it is the characters in all the nominated movies that make them distinctive. In a diverse field, this might be what most unites them.

"They are all about characters trying to come to terms with the complicated moral world we live in," Bird says.