'Star Wars': An inside look at how the Darth Vader comics fit with the films

What is approved and what is turned aside.

— -- In a rare look inside the world of "Star Wars," Marvel Comics authors Kieron Gillen and Charles Soule, who work on the Darth Vader franchise and other spinoffs in the comic books, gave ABC News a glimpse into how the story group at Lucasfilm works.

The story group, the nucleus of Lucas, has the job of ensuring that all the stories that flow between the books, comics, games, movies and more are cohesive.

Clayton Sandell on ABC News Digital's show "Inside Marvel" asked Gillen and Soule to "pull the curtain back" on what it's like to work on a project like the Darth Vader story that reaches into so many different mediums.

"It's not like they are trying to step on stories on anything like that," Soule said of the experience of authors like him working with the story group. "They propose a spot in the timeline, then it's like, 'What would you like to do with the character?'"

Soule said it's a "back and forth" in the story group.

"There's lots of outlines, kicking ideas around and eventually it turns into a comic," he said.

For Soule, his series follows Vader right after "Revenge of the Sith" and right after Anakin Skywalker has transformed into Darth Vader.

"The great thing about it for me was that onscreen, we've only seen Vader in his armor for 10 seconds before my story begins," he added. "It's Vader year one. He's a baby Sith lord."

Gillen got to write Vader right after "A New Hope," when the Sith lord failed to protect the Emperor's prized Death Star from blowing up.

"In 'A New Hope,' Vader is just kind of following orders. In 'Empire,' he's just killing people randomly," Gillen explained about his run. "It's kind of an implied fall and rise."

Gillen also got to add some big reveals to the canon story such as Vader's realizing that Luke is his son well before the events of "The Empire Strikes Back."

"It's the flip of 'I am your father,'" he said about his contributions to the "Star Wars" legacy.

As for what sorts of ideas get rejected from the story group, the two acclaimed authors said it isn't what you'd expect.

"Occasionally something really minor gets rejected and you don't know why and you watch the next movie and go, 'I know why!'" Gillen said.

Gillen had wanted to use a costume in his series that was turned down and which he later saw used in "Rogue One" for a completely different purpose.

Soule also writes the Poe Dameron series for Marvel and "Star Wars," and a very similar thing happened in his franchise.

"There was a point where we wanted to give the main villain this all-white costume," he explained. "They said, 'Maybe let's not go white.' Then I saw 'Rogue One' and realized [Director] Krennic was dressed in these all-white uniforms."

ABC News, Lucasfilm and Marvel are all part of parent company Disney.