Though the series that brought them widespread acclaim in the comics world ended in December, "Locke and Key" creators Joe Hill and Gabriel Rodriguez greeted a packed house when they took the stage together at Comic-Con International in San Diego. During the hour-long Q&A moderated by IDW Publishing Editor-in-Chief Chris Ryall, Hill and Rodriguez reminisced about the series, detailed some of their future plans, dropped hints about new "Locke and Key" projects, and gave away many, many replicas of the series' magical keys to lucky audience members who could answer trivia questions. They also spilled the beans on a mind-boggling crossover they were planning at one point that never saw print in our reality, but which certainly has a shelf of honor in the Library of Dreams.

Hill opened the panel by standing a chair and yelling, "Say hi to Twitter, everybody!" The crowd waved as Hill snapped a picture to share with his followers, demonstrating the transparency and engagement he's become known and loved for.

San Diego says hello: pic.twitter.com/hMqdB6j6Re- Joe Hill (@joe_hill) July 26, 2014

The panel quickly went straight into audience questions, but not before a quick joke from Hill.

"Maybe we'll get into the forthcoming 'Locke and Key'/'My Little Pony' crossover that IDW is doing and that we're all very excited about," Hill quipped. The audience laughed wildly at that, but Hill soon had them gasping for breath as he revealed an actual crossover that nearly happened: one with Neil Gaiman's "Sandman" universe.

"We were in talks for a long time, and had provisional permission, to do a 'Locke and Key'/'Sandman' crossover. Y'all remember the key to Hell? The idea was that the Lockes would have created that key, or a duplicate version of the key, and would unlock Hell. It would be a story of Chamberlain Locke, set in the past, and he would have wandered through Hell, and then the House of Mysteries and the House of Dream, and he would have crossed paths with Morpheus and Lucifer and Death, and a lot of the great characters from Vertigo. It was one of these things where DC said 'Yes!' But we have a lot more ideas than we have time and we never really steered around to it and then we finished the series," said Hill.

"Yeah, and the problem with mentioning things like that publicly is it just now feels like now we're never going to be able to do this," Ryall said. "If we keep it secret it feels possible."

"But the 'My Little Pony' crossover? A done deal. That's definitely going forward," Hill joked again.

The Q&A kicked off with a question about Rodriguez's upcoming "Little Nemo: Return to Slumberland" comic, coming out from IDW with writer Eric Shanower.

"It has been great," Rodriguez said. "I love McKay's work, I love that universe, I love that kind of story. I think that kind of story has been pushed away in recent comics. We need to bring back that kind of imagination, fantasy, and gratuitous joy to comics for new readers and families to share together. For me this is especially appealing because it is the first time I will have to show my complete work to my kids. That's an improvement for me!"

"I've seen the pages and I think it's Gabe's most beautiful and most wonderful work. I think it's some of the most beautiful pages I've seen in any comic anywhere in the last three or four years." Hill said. "I think people are going to be flattened by what he's done."

"The challenge with Gabe is that we want him to draw everything we ever do," Ryall admitted.

The next question was addressed to Hill, asking about keys that he had dreamed up that didn't make it into the story. "There was one key that was mentioned in one of the very first issues that let you change your age. I always assumed I would find a story to stick that into and I never did. We had a lot of ideas for possible keys and possible adventures, but in the end we really wanted to keep the story tightly focused on Tyler and Dodge and Rendell, that sort of tragic triangle. We didn't want to take the risk of dragging the story on for too long; we didn't want to lose the focus," Hill said.

However, one of the biggest pieces of news for fans of the series is that Hill has more "Locke & Key" planned. "We've got two stories for a book called 'The Golden Age' which is about a somewhat happier time in Key House," he said. "The two stories that have already been published in that are 'Open the Moon' and 'Grindhouse,'" referring to the two standalone issues of the series. "There's going to be a few more of those to finish the book because we've got a couple more stories we want to tell, set between 1905 and 1935. We will get to explore some of those other keys and possibilities."

An audience member asked about viewpoint characters for the creators, wondering who they identified with most as they were bringing the story to life. "Probably Detective Mutuku," Hill said. "There are all of these impossible events that he's borderline a witness to. He's sort of implacably keeps picking at it, trying to make all the parts fit together. For thirty-six issues that's what me and Gabe both were trying to do was figure out how to eloquently make all the parts make sense.

"I always wanted to give Mutuku a much bigger swordfight," Hill continued. "I implied that there was going to be one, but in the end the best he did was kick a kitchen knife out of someone's hand."

"That sequence that you wrote was complex enough! Between that and the mason jars I still have nightmares!" Rodriguez said, referring to a sequence in which hundreds of jars containing tiny characters are tumbling to the ground, that he found incredibly time-consuming to draw. "I realized that Joe has a special ability. When he sends you a script and says, 'Don't worry, this page only has three panels!' and then you read the panels and they are those in which you have, like, eleven panels set into one, and that's even tougher to do! So, thank you."

"In some ways I also feel like Bode, where you unlock his head and can see all the thoughts that are inside," Hill said. "'Locke and Key' was like that, like some world that just swirled around in my head and in Gabe's head."

"I think we all felt like Bode at some point," Rodriguez added, "discovering this world and seeing what it was offering. But on the other hand, for me, it was very appealing to work with the drama and conflict of some of the adult characters. Certain parts of the story with Nina Locke were very hard because you felt like she was a real person, and you suffered with the suffering. I remember when we were working on the last issue of 'Crown of Shadows' where Nina Locke crashes at the end of that book. That was a terrible month to work because I was constantly in the head of that woman, suffering like hell in that part. But in a way it was a blessing for us to get to tell a story where the suffering of the characters was so real. It was an amazing experience."

The writer was also able to discuss his experience writing in different mediums -- comics and prose. "I do have these two lives: my life as a comic book writer and my life as a novelist and short story writer. My life as a comic book artist came first, and in a lot of ways that is my natural home" Hill said. He went on to describe his early days, writing three novels that he couldn't get published and all but giving up on having a career as a writer at all. But one of his short stories was published, and eventually read by an editor at Marvel Comics, who asked Hill if he had any interest in "writing about guys in tights punching each other."

Hill's first assignment was "Spider-Man Unlimited" #11 in 2005. "I totally choked, it was a terrible story," he confessed, "but it pumped me up and made me want to write more comics. Growing up, all of my favorite writers were comic book writers: Neil Gaiman and Alan Moore and Jamie Delano and Frank Miller. I was really charged up to do more in comics and that's how things got rolling."

"We should point out on the Spider-Man story that, whatever Joe thinks about the writing, it was saved by some amazing artwork by the late Seth Fisher," Ryall interjected. "The lesson there is that if you pair Joe with an amazing artist, you're never going to know if the story sucks."

"It's true! That's well-said." Hill agreed, to laughter from the audience.

Rodriguez recalled getting the first script for "Locke & Key" from Hill and being amazed at his mastery of the craft. "I have to say that when they sent me the script for the first issue of 'Locke and Key' they said 'This guy has never written a comic book' and I just couldn't believe it," Rodriguez said. "It was the most perfect comic book script I'd ever read, and I immediately realized it was going to be something big, and a big opportunity for us."

In response to a question about disagreements over the course of the series, Hill reassured the audience that he and Rodriguez actually grew very close the more they worked together. "I learned as much about the characters in 'Locke and Key' from his drawings as he ever learned from me from stuff that I wrote," Hill said. "As we went on, the process became more and more collaborative." Hill even admitted that a key plot point in the final arc actually was Rodriguez's idea. "We were in Pittsburgh for the filming of the 'Locke and Key' pilot for Fox TV. And the 'Locke and Key' series is now entering its third hit season in my imagination. But the best thing about being on set was Gabe and I had this unbelievable stretch of time -- five nights -- to sit in the restaurant at the hotel and just make shit up!"

"Lots and lots of shit," Rogriguez confirmed.

Hill continued, "At one point Gabe just said 'I don't understand why Tyler doesn't just make a key to unlock demons from souls.' And I was just like--" Hill made a gape-mouthed expression which drew a chuckle from the audience.

"We quickly got to a point in which the story started speaking to us," Rodriguez added, "and the characters started behaving according to their own needs and impulses. As time passed, I think it was even more difficult to find a place to disagree because the story was getting even more tied in itself."

Although "Locke & Key" came to a definitive end, Hill addressed a question about whether the characters would remember any of the magic they experienced over the series' run once they became adults.

"I think at the end of the series, they are already forgetting," Hill said. "All of these kids are just tipping over the point where they're not kids anymore, so we have this story about how maybe methane gas was getting loose down in the caves and causing people to hallucinate monsters, and it was really just a cave-in. You can see the grown-ups trying to sell themselves on that, and you can almost imagine the teenagers a couple of years later when they're in college having sold themselves on that, too. I think all of them are forgetting. The really interesting thing is that I think even Tyler forgets, after a while. Maybe that's another story."

Rodriguez continued, "I think that one of the points of the story is at the point when they become adults, they are going to forget about the magic and rationalize all of that. But the interesting thing is that everything that happened to them made them the people that they finally were. That's the point of the story. After all of their journeys, they became something different, and hopefully an improved version of themselves. That is the legacy that they are going to carry with them for the rest of their lives. That is the point of growing up."

In terms of the depth of Hill's stories, he said his method was "sheer panic and terror."

"I'm always afraid the reader is going to go load up YouTube and watch videos of funny kittens inside wine goblets and stuff," he said. "As a writer, you just can't screw around. There has to be a little explosion of awesome in every scene, and usually it has to come from character. I think this is the lesson of Joss Whedon's work: when you think about how great 'The Avengers' is, or how great 'Firefly' is, you remember these little explosions of awesome. But it's never someone punching someone or a building collapsing. It's always somebody saying something. It's a line where you think, 'My God, that's so perfectly them!'"

The biggest challenge for Rodriguez wasn't actually drawing a character -- it was drawing an inanimate object that was just as important to the plot of the series. "For me, by far the toughest character to work with in the series was the house," Rodriguez said. "I am an architect by training, so when we started working on the book I got this idiotic idea to make the house an actual architectural project that could be functional. So I made the blueprints for the house and made a 3D model and then I was cursed by it for the rest of the series. But as soon as I read the pitch I immediately realized that the house was going to be a character in the story, and the one that was going to carry the heritage of the Locke family throughout the ages. It finally came out pretty well, so it was one of those things that you sweat over a lot, but in the end it pays off big.

"As for the actual characters," he continued, "I loved working with all of them and sharing my daily routine with these characters, but the one that was a real nightmare to draw was Scott Kavanaugh. Joe had this great idea of him having his body filled with tattoos that I started to draw in all these Celtic designs, and then I realized, 'Oh my, I have to draw this guy from all these different angles!' Every time I drew him I had to have six or seven sheets of paper with him printed in all these different positions just to make sure the tattoos matched."

Rufus unexpectedly became one of the heroes of "Locke & Key," and the first strange thing readers notice is that he doesn't have a keyhole in the back of his head, so Dodge can't use the Head Key on him.

"I was trying to suggest that there is something fundamentally mysterious about the thought process of the autistic and people who have Down's Syndrome," Hill said. "I wanted to suggest that something that is generally looked at as a disability could make him unusually powerful and dangerous to Dodge, and Dodge may not see that. He can't fool Rufus, and Rufus' mind is a kind of closed space."

"It's in his nature," Rodriguez added. "He is by himself and different, and that protects him from the schemes of Dodge."

"I knew pretty early on that Rufus was going to finish off Dodge," Hill continued. "Dodge just was too arrogant to see that Rufus could be a threat to him because knew the truth and his basic decency couldn't be warped."

Hill was asked about the development of the story and what point he started writing from: from the kids in the present, the origin of the keys, the detailing of the book's deep mythology. "For the first four or five issues, I was just flying by the seat of my pants, making shit up as I went along," Hill said. "And then I had an opportunity to ask a question of Alan Moore in an interview, and I said, 'How important is it to know the answers to your mysteries when you're going into a story?' and he said, 'Only a total asshead would set up mysteries they don't know the solutions to.' So at that point I made a bible and talked to Gabe about it. At first the bible was very big and explained how everybody got everywhere, but when we got around to telling that story in 'Clockworks' a lot of that unnecessary material just fell away."

Another reader asked about the development of the character Sam Lesser, the angry youth who kills the patriarch of the Locke family and sets the story in motion. "I mentioned earlier on that I had written three novels that I was never able to sell," Hill replied. "One of them was a book called 'The Briars,' and it's about a long hot summer where there's this young, gifted, but miserably unhappy young man who falls in with a thuggish older boy named Al Grub, and this younger boy who is a genius but who has no other friend, and no real emotional inner life, and his name was Sam Lesser. The two of them go on a killing spree in a small New Hampshire town. So I wrote this book, and it wasn't actually all that good a book, but the relationship between Sam and Al was interesting. They became the opening of that first issue; it was basically part of 'The Briars.' And you know, sometimes I think the story didn't need Al Grubb..."

"I think Nina Locke would agree with you," Rodriguez joked.

The last question of the panel finally touched on a long-time source of hope and curiosity for all "Locke and Key" fans: the 2011 pilot for a "Locke and Key" TV show that never materialized into a regular series. Recent rumors had suggested that the pilot's producers were interested in developing the story into a film trilogy, and Hill offered all the details he could. "Alex Kurtzman and Bob Orci [of "Sleepy Hollow" fame] produced this great pilot that never aired, unfortunately. We did air it here at San Diego Comic-Con a few years ago, maybe some of you guys got to see it. It came out really well, but unfortunately Fox went with 'Alcatraz,' which I believe is in its third hit season!" Hill said, sardonically. "Alex Kurtzman is very devoted and has pushed very hard for 'Locke and Key.' He was able to bring the film rights over to Universal, Universal would like to do it as a trilogy. They have a screenwriter working on it who apparently has an idea to knit together two books in each film, which I think is sort of intriguing but I don't know if it will work, I would have to see the scripts. I do have hopes that there will be a film from Universal in a few years."

"You never know if these things get to happen or not, especially with the movie business," Rodriguez said. "Things sometimes change overnight from going into ptoduction to dying. But what we are very comfortable about is that the people that's involved in trying to develop this project really love the source material and are passionate about the story and the characters. We are pretty confident that, if they manage to make it happen, probably it will be pretty close to the spirit of what the book is about. That is what we hope for."