Gravity: Written by Alfonso and Juan Cuaron

Billy Ray, who scripted “Captain Phillips” says:  “What the stars are looking for in a character is dilemma. Those are the playable moments.”

Actors above all crave “red meat,” in the phrase of Tracy Letts, author of carnivores’ banquet “August: Osage County.”

“The truth is, there’s a lot of shitty writing in this business,” says Letts. “So when you get an opportunity to get some good writing, whether or not you’re a movie star, you want to knock it out of the park.”

Some scribes envision a dream lead who actually signs on (as Ray did with Tom Hanks), while others are handed the lead on a platter. Recreating hyperactive hustler Jordan Belfort for “The Wolf of Wall Street” was easier, according to Terence Winter, with Leonardo DiCaprio attached. “Knowing what he looks and sounds like, I was able to filter Jordan’s voice through Leo and write the character that way.”

Many simply try to craft a killer part. Jonas Cuaron says he and his father Alfonso Cuaron saw “Gravity” as a “rebirth story” of a great, vital soul, and netted great soul Sandra Bullock, who “is normally the way the character ends.”

On “Saving Mr. Banks,” Kelly Marcel surrounded her computer with photos of P.L. Travers and Walt Disney and depended on the story to sell itself. “At a press conference in London, Emma Thompson said she read the first page and said ‘I’m doing it.’”

An ideal matchup may take time. During the 20-year development of “Dallas Buyers Club,” Craig Borten and Melisa Wallack saw three biggies come and go before being “blessed” (their word) with Matthew McConaughey, who inspired revisions.

“Once you know you’re getting Matthew, you know the comedy has to be brought down,” Wallack says. “He’s so affable, so charming, the lightness is going to be there, so you can move it somewhere more intense.”

There’s no single path to a mutually satisfying collaboration. Work conflicts restricted Letts to only a single-day table read on “August,” where he was inundated with “basically the same questions any actors ask on the first day. They all sort of come down to: ‘What do I want, and what will I do to get it?’”

Actors-scribes relations are more often hand-in-glove, complete with on-set office and constant contact. Remembers Cuaron, “Sandy would come out of hanging in the rigging for hours, and she’d still find a few minutes to work with me on the monologues and so forth.”

Marcel notes, “Emma literally won’t change a word.  She’ll find a way to make every word work,” while Hanks aimed to “add in little words and mannerisms.” The Mouse House mogul habitually added the phrase “and things” to his sentences, so “Tom and I did an ‘and things’ pass, finding places where we could insert it,” says Marcel.

Those who would invite stars to the party need to proceed with caution, Hawke says. “When people say they’re writing ‘a Tom Cruise part,’ ‘a Will Smith part,’ it’s always a copy of another movie. You’re never going to make anything interesting chasing that rabbit.”

Richard Linklater reports, “some veteran actors feel they have to protect themselves. At some point in their career, they did exactly what they were told and they weren’t good. All their fears were realized on screen, so they go, ‘I’m not going to be that vulnerable again. I’m going to stay in my comfort zone and not risk being bad. Or silly.’”

When your lead balks, Winter advises, “Try to state your case as gently but convincingly as you can.” Marcel adds, “You’ve got to pray you have a strong producer and director who’ll protect you, and who know what’s good for the script.”