It was an hour of aliens as Dark Horse Comics brought "A Universe of Terror Drawn to One Panel" to Comic-Con International in San Diego. Moderated by Dark Horse Editor in Chief Scott Allie, the panel featured several of the creative minds behind Dark Horse's upcoming crossover event. Artists Juan Ferrerya ("Prometheus") and Ariel Olivetti ("AvP") joined writers Paul Tobin ("Prometheus"), Christopher Sebela ("AvP"), Joshua Williamson ("Predator"), and Chris Roberson ("Aliens") for a behind the scenes look at the creative process behind the "Fire and Stone" crossover, which will link all four books together.

RELATED: EXCLUSIVE: Olivetti, Mooneyham, Reynolds Illustrate Dark Horse's "AvP" Franchise

"It's actually been a lot of fun," said Tobin. "All the writers live in Portland so we can all get together, usually at Scott's house ... It's been really this fun collaborative process."

The writers enjoyed their collaborative sessions for weeks as they forged the details of the franchise mixing story, until January, when they encountered a significant setback.

"We were meeting for a while. We had worked out a lot of stuff," said Allie. We were getting approved by Fox and the film producers and -- well, then something happened."

The creative team had a variety of ways to describe what happened, some more diplomatic than others, but the end result was that they had to start the story over from scratch. A frustrating setback, considering entire issues had already been written and drawn.

"We walked into Scott's house and we were offered sheets of paper and a drink," said Roberson.

"After all the revisions came through I was kind of a hollow shell for most of that meeting," said Sebela.

However, going back to the drawing board wasn't without its advantages, and everybody agreed that the story they are working on now is more satisfying than what they had previously written.

"They actually opened up a lot more of the toolbox for us," said Tobin.

With some of the writers approaching the project from a deep fandom and others coming in with little prior knowledge, the creative team has benefited from the range of perspectives as they work to establish the universe of the story they are telling. Part of that task is the creation of new alien creatures, which is where Ferrerya became involved.

"It was really fun designing those," said Ferrerya. "I had to research and study all the aliens, and also the big world in books. I had so many designs in my head and so little time to do everything but was really fun."

Although Ferrerya was also affected by the decision of start from scratch, the creative team did manage to save many of his pages to be used in the new story. However, the artist couldn't commute to the Portland meetings from his home in Argentina. It was artist Patrick Reynolds that ended up designing many of the characters in the story since he could sit with the writers and listen to them describe every aspect of the character.

"That actually resulted in Patrick naming most of the characters," said Allie.

Maps have also become a major storytelling tool for the writers. Described as "one step away from a D&D campaign," maps of spaceships and alien worlds are used to ensure a sense of consistency between the different books. And much like a D&D campaign, it took a while to figure out what role everybody would play.

"That first night that we met, we didn't know exactly who was going to write what book," said Williamson.

Tobin was selected for "Prometheus" in order to put him together with Ferrerya. Williamson thought he might be put on "AvP," but his work on creating Ahab, a Predator going on his last great hunt, got him selected for "Predator" instead. "AvP" instead went to Sebela, which suited him just fine.

"I kind of walked into the room thinking that was the book that I wanted to do," said Sebela, who had a hard time complimenting the two films in the franchise. "I felt that the biggest challenge to me was to write an 'AvP' that was great and to give due service to both Aliens and Predators. I spent whole childhood sitting around trying to figure out how Aliens would fight Predators. So the fact that somebody was going to pay me to do that was well beyond any of my weirdest fantasies."

Allie admitted that Kelly Sue DeConnick had told him about Sebela's encyclopedic knowledge of the franchise that came from being a lifelong fan.

"Kelly told me that you were the expert on all that nerd knowledge and that you knew these franchises," Allie said to Sebela. "That was one of the things that got you in the room in the first place."

With Ferrerya translating, Ariel Olivetti expressed how much he enjoyed the new challenge of drawing a more cinematic looking story.

"During these twenty years he's been drawing super heroes," said Ferrerya, translating for Olivetti. "With this story and with these characters, this is the first time he's drawn comics to feel like a movie."

Showcasing Ferrerya's art, Allie put a preview page of "Prometheus" on display, showing off the characters of the story as they come across a dangerous location known as "The Killing Field."

"It's one of the first times that they realized that it's not as hospitable as they might hope," said Tobin. "That top scene right there is one of the ones we looked at and said, 'Patrick, make us a map of this entire area,' so that's all to scale ... We wanted to make sure that if you see something in the background or if you see something in the world, that it is actually a world."

"Patrick making those maps made it much more like a D&D campaign," said Roberson. "We literally had questions that were answered by the map, so the story is structured based on the setting."

Although Dark Horse signed on to do a "Prometheus" comic two years ago, it is only now that the company has been able to work on a book, with Allie saying that the was such a secrecy surrounding the film, it wasn't possible to do a comic. "No real conversation about the story happened until after that movie was out," he said.

As far as continuity with previous "Aliens" or "Predator" comics, the new storyline won't necessarily be written with those books in mind.

"It's not that those things didn't happen," said Roberson, "but we're crafting a story for people who only know the films."

Allie agreed, saying that Dark Horse didn't want to "strangle this story with the twenty-some years of comics."

Likewise, the panel also addressed how much of the "Prometheus" movie would be used for the upcoming story.

"It's like this weird duel adventure where we're going to this place 26 light years away to this wonderful adventure and while they're there its an entirely different adventure than what they thought," said Tobin, who inadvertently sparked a side discussion from Roberson about light speed travel and movies.

Without giving away any spoilers, the creators told the audience that they've been working to stick close to the theme of the movies -- namely, the stewardship of life and the relationship between The Engineers, humanity, and androids. They did, however, reveal that the official name for the black goo in "Prometheus" is called "Accelerant."

When asked directly if the two "Aliens vs. Predator" movies would be canon, Sebela earned a round of applause for answering, "No."

"I went back and watched them before I started writing, just to refresh myself, and the first one is not bad," said Sebela. "But no. I definitely try to approach it from as fresh a slate as possible."

For the most part, the creative team will be informed by "Alien," "Aliens, "Predator," and "Prometheus," without getting too involved with the content of the rest of the sequels.

"Fire and Stone" will be a set of four four-issue mini-series, followed by an omega series written by Kelly Sue DeConnick to wrap it up. While they all come together and share a unifying theme, Allie explained that each mini-series will be its own story.

"Each four issue mini-series is its own thing. If you just read 'AvP,' you get a whole story," said Allie. "Theme was a very important way to make sure this was all one package."

"Prometheus" and "Aliens" are due out in September, "AvP" and "Predator" are scheduled for October, and the "Omega" series begins in February.