Over the previous nine seasons, Supernatural has introduced a lot of characters, but few have gone on to secure recurring roles. Fewer still have clicked with viewers the way Charlie Bradbury has. She even scored her own Funko Pop! vinyl figure.

Played by Felicia Day, Charlie is a LARPing computer expert with a fondness for Star Wars, aliases and, um, unusual tattoos who was introduced to the Winchester brothers in Season 7, only to return (twice!) in Season 8 before leaving with Dorothy to help free Oz in Season 9.

However, as most fans know by now, that wasn’t the last they’ll see of Charlie: She returns from Oz this season in an episode the show’s producers are keeping under wraps.

But while speaking with Supernatural writer Robbie Thompson about the launch of Marvel’s Silk series, CBR News took the opportunity to ask him about the creation of Charlie Bradbury, the appeal of the character, and his hopes for her future.

CBR News: One of the reasons I think Supernatural fans are so invested in the show is not just because of the Winchester brothers, but the great cast of supporting and recurring characters that surround them. What is it about characters like Bobby Singer, Garth, Kevin Tran, Castiel and now Charlie that has fans so excited about them and clamoring for their return?

Robbie Thompson: That's a great question. I think the core DNA of the show is Sam and Dean and the relationship they have and the many directions that gets pushed and pulled. And the reason I think these supporting characters pop so much on our show is that there's such a great opportunity with all these characters to see different sides of our main characters.

For example it's been really fun as a writer to watch Sam and Dean interact with Charlie. So I think these characters -- whether it's Bobby, Garth, or even Crowley -- allow us to show different sides of our protagonists. Also in private moments they let them reveal things that they're maybe not ready to reveal or able to reveal to their brother. Any character is a mirror into another character's soul, and I think all these characters that you brought up whether it's Bobby, Charlie, or any of our supporting cast reflect and also show the contrast in this core relationship.

They're also so much fun to write for as actors. Because as actors they bring a completely different dynamic to the well-established one between Jared [Padalecki] and Jensen [Ackles]. For example, it was always a thrill to write for Jim Beaver because he brings a completely different energy to the scene and the dynamic that they all have as actors.

It's the same with Felicia Day. Felicia came to play from day one. She really stood her own and brought out a great dynamic. As actors they all found a really fun rhythm. I think it's a lot of fun, and I'm speaking as a fan, to watch the core dynamic get tested and sometimes challenged by these supporting character and what these actors bring. I remember last season when Tim Omundson was Cain, his scenes with Jensen's Dean and Mark [Sheppard]'s Crowley really popped because you could tell they were all having a great time on set and it really translated to the characters.

You created Charlie for the Season 7 episode, "The Girl with the Dungeons and Dragons Tattoo." What inspired her creation? And how fully fleshed out was the character when you began writing the episode?

What inspired her creation was a couple of different things. Obviously with the title, Lisbeth Salander was definitely an inspiration. I love that character. I love [Stieg Larsson's] books and the movie, but we wanted to find a different sort of spin on a hacker character.

The original pitch was actually completely different. I knew that the story was basically going to be very myth-based, and my pitch for it was, "Hey, could we do an episode like the movie The Insider, where there's this Russell Crowe character within Dick Roman's empire who is a whistleblower?" That eventually evolved into something much, much different, and I think much, much better thanks to [then showrunner] Sera Gamble, who is a fantastic writer and was a fantastic boss.

Then with regards to how fleshed out the character was? I've been lucky enough to introduce a few new characters on the show and as a writer I always like to write out a very detailed back story. Knowing a character's history helps me find their voice. Nine times out of ten none of that stuff will end up on the page. [Laughs]

It's just work that I do as sort of due diligence, but one of the reasons Charlie's character was introduced in general was that episode was the one where we thought Jared was going to have his first child. We wanted the boys to be in that episode together too. So we knew we needed a character that was really fleshed out and could hold their own for the days we were shooting because Sera was obviously concerned and wanted to make sure that Jared could be there for the birth of his child. The funny thing was that Jared's son ended up being born while we were shooting the next episode. [Laughs] So it ended up all being for naught.

I wanted to make sure Charlie was a fully fleshed-out character, and I drew up a pretty detailed backstory. Because we brought her back for three other episodes we got to tell about 75-80 percent of what was in that original document. Some of it changed.

As an interesting side note, I did not meet Felicia until after her first episode was shot, but a lot of the choices that she made were so spot-on due to some of the backstory. The notes she was playing in between beats and the history she brought to the character to make her feel fully realized, a lot of it was on the exact same page as I was even though we hadn't actually met and we hadn't shared the character's backstory. So it's a real testament to her as an actor. She made some really strong and great choices.

So Felicia was cast after you wrote the episode?

She was. I finished the original draft of the script and handed it in. I felt good about the draft, but I was nervous because there was a lot of Charlie Bradbury in that episode, and I didn't know who the actor playing her was going to be. You never know with these things if you'll get an actor that can carry full days of shooting.

Then I'll never forget. Sera Gamble sent me a very short email and all it said was, "Felicia Day. Booked. Charlie Bradbury." And I was so excited. I did another pass on the script after she was cast, and then Sera did another pass on the script as well, because once we knew we had Felicia we knew we had a great actor and we could give her a few more jokes. We could let some of that history play a bit more, and let her go toe-to-toe with the boys. So we were so lucky to get her, and we're so lucky to have her.

You wrote all of Charlie's subsequent episodes as well. What was it like collaborating with Felicia in bringing that character to life?

It's funny, I remember watching her in dailies for her first episode, and my first thought was that I cannot wait to bring this character back. She made so many great choices as an actor with lines that weren't funny and she made them funny, and some that were funny that she added a lot of weight and history to.

In a couple of her episodes there are references to The Empire Strikes Back, of the Han Solo and Princess Leia Lines, "I love you"/"I know." I still love the way she played that in the dailies for "The Girl With the Dungeons and Dragons Tattoo." I had written it as sort of a jokey, ha-ha moment, but she played it with such history, like she had heard that line so many times, and she played it in a very genuine way. It was really unexpected, and I remember that being the first bit of dailies that I saw of her work. So I really wanted to bring her back.

When you have an actor like that you that you know you can really lean on from both a performance and storytelling stand point it just makes you want to write for them more. Also, she has such great chemistry with the boys that you'd even want to write scenes where it's just the three of them hanging out.

So it's been a great collaboration. Felicia deserves a lot of credit for bringing that character to life, and frankly she's the reason why that character keeps coming back. I have the great pleasure of writing that character, but it's really her strength as an actor and her choices as an actor that's made it possible to bring her back so many times. We're really lucky to have her.

Let's talk a little more about Charlie's experiences on the show and her relationships. From my perspective she appears a little closer with Dean than she is with Sam, is that correct?

I guess so. A lot of people have pointed that out. For me it's just one of those things where it just kind of shook out that way from a timing standpoint, but I think there is a little bit more of a connection there. Hopefully in the upcoming episodes you'll see a little more of a connection with both brothers.

I think she loves both boys, but there's definitely a big brother-little sister vibe to the relationship between all three of them. I think she and Dean though have just been through a couple more adventures together. I think there's a part of Charlie's character that's able to access the secret geeky part of Dean Winchester: getting him to LARP, which is something he wouldn't normally do, getting him to appreciate the logic behind a video game, or appreciate Game of Thrones. I think she's able to tease that part out of him.

At the same time, I think she has just as much a bond and a connection to Sam. They're both computer-literate, nerdy, hacker types. That's something I hope we get to explore as well in future episodes.

As you said, Charlie's relationship with the boys is a big brother-little sister one and not a romantic one, which is cool and refreshing. That's partly because Charlie is Supernatural's first major human LGBT character, right?

I believe so. She definitely is the most prominent, but for me Charlie was never going to be defined by her gender or her sexuality. She came fully formed to me at the very beginning, when she was introduced. The first bit I wrote for Charlie was her having that private moment in the elevator and dancing to a song like nobody was watching. She's got this incredible spirit and drive. I love getting to explore that every time we get to play with her character.

Let's move to Charlie's return this season. I understand if you have to be vague to avoid spoilers since it's a ways off, but the last time we saw Charlie in Season 9's "Slumber Party" she was embarking on a great quest to help liberate Oz. What kind of shape will Charlie be in when she returns from Oz?

All I can really say is Charlie definitely comes back from Oz and she',s brought back something that's pretty scary. She's going to have to confront it with the boys.

One of the great things about knowing you're working with Felicia is she, as an actor, really gave us permission to let her character grow. So we've always tried to tell a new chapter of Charlie's life when she appears. I always believe that every character is the hero of their own story and that' definitely true with Charlie. This episode is another chapter in her ongoing journey and continual growth as a character.

Finally, can you talk at all about the dynamics we'll see in the episode where Charlie returns? Might she have some scenes with "Demon" Dean?

I can't really say anything about that, but people have asked about Charlie and scenes with other cast members and characters. I can't comment about that for this episode, but it's definitely something I would love to see. I would love to see her in scenes with Castiel and Crowley. We actually had a scene with her and Crowley in the "Slumber Party" episode that got cut.

I love writing for Charlie Bradbury and I'm very excited that she's returning for Supernatural's 10th season. I certainly hope that this isn't the last time we see her. I hope she's a character in the Supernatural universe for years and years to come.

Supernatural airs Tuesdays at 9 p.m. ET/PT on The CW. Silk debuts from Marvel in February.