Last fall, The CW advertised "Amell Wednesdays," promoting the fact that "Arrow" -- starring Stephen Amell -- aired back-to-back with "The Tomorrow People," with Stephen's younger cousin, Robbie Amell, as the lead.

"The Tomorrow People" only lasted one season, but the cousins are both back on The CW, and now inhabiting the same DC Comics-based fictional world. On tonight's episode of "The Flash" -- the show's third overall, in an inaugural season that's set rating records for the network -- Amell debuts as Ronnie Raymond, Caitlin Snow's (Danielle Panabaker) presumed dead fiance.

Comic book fans know that Ronnie Raymond is destined to become the nuclear-powered superhero Firestorm, a long-running DC superhero set to join series star Grant Gustin in the show's pantheon. "The Flash" producers -- including "Flash" and "Arrow" co-showrunner Greg Berlanti, who Amell worked with on "The Tomorrow People" -- have been clear that Amell will take on that identity sooner rather than later. In fact, the role of physicist professor Martin Stein -- who in comic lore, fuses with Raymond to create Firestorm -- has already been cast, with "Alias" and "Argo" alum Victor Garber playing the part.

CBR News spoke with Amell about the surprisingly smooth transition from "The Tomorrow People" to "The Flash," his mother-assisted comic book research, reuniting with Garber and the "powerful" upcoming debut of Firestorm, which he says viewers will see this December.

CBR News: Robbie, your first episode of "The Flash" is airing this week, so you must have been working on the show for a while now -- how much fun has it been to be a part of this blossoming, and clearly well-received, shared universe between "The Flash" and "Arrow"?

Robbie Amell: It's awesome. When Greg Berlanti asked if I wanted to do it, it was a no-brainer. Of course I'd want to do it. It's been fantastic. I shot this episode a couple months ago, and I got to set and it was 70 percent of the same crew as "The Tomorrow People." It was like coming into season two. It was a lot of familiar faces, a lot of people I was really happy to see. Grant and I had talked a bunch on Twitter and all that -- when I met him, I was like, "I feel like we've hung out before!" Danielle and I have a few mutual friends, so we hit it off right away. We just had a blast. It was really nice.

The first scene that I shot was a celebratory scene that gets cut early by the particle accelerator having a little mishap, but it was nice to shoot a celebratory scene -- because I was really happy to be there, and I was really happy to be a part of it. I'm just excited. I'm a huge fan of the show. Greg sent me the pilot when I [was cast], and all I thought was, "Holy shit, this is going to be huge." Second episode was awesome, and I'm pretty excited for the third episode.

How familiar you were with this world going into it? On a simplistic level, I'd expect you were pretty familiar with "Arrow" for obvious reasons, but obviously you're a busy guy and who knows how much time you have to watch TV. Were you keeping an eye on all of this before you became a part of things officially?

I'm very familiar with "Arrow." I was a huge fan of "The Flash" comic book, and when Greg Berlanti was auditioning people for "The Flash," he gave me the sides, and he was like, "I want you to take a look at these. What do you think? Are these good audition scenes?" I read them over and was like, "Damn, this sounds awesome." That was when they were testing people for Grant's role. It was cool to watch it come to be, and it's so many of the same people that were working on "The Tomorrow People," so I had heard about it while it was happening -- we had the same visual effects supervisor, Armen [Kevorkian], who is fantastic. I was already pretty close to the project when they started shooting, and when I became a part of it.

As far as the world goes, I'm a huge DC fan. I'm a huge, huge Batman fan, since I was a kid. I grew up being Batman for Halloween, and watching the TV shows, and playing the video games, and reading the comics. But to be honest with you, I wasn't very familiar with Firestorm. I knew of him, but it wasn't a character that I had a whole lot of knowledge [of]. So I got a care package from DC, and my mom -- who I don't think had ever been in a comic book store -- I was home in Toronto when I got the role, she came over and gave me a box full of comic books she had picked up. She had raided comic book stores for everything they had on Firestorm, which was the cutest thing I've ever seen.

It was great. I had a bunch of flights; I do as much reading as I can on airplanes. I just read up on that character, and got a sense of what I thought would be fun to bring to him, and I hope people like it.

So when you were doing that research and delving into the source material, what was some of the traits that stuck out to you about the character that you found interesting, and wanted to bring in your own way to this role?

I like that there's a sense of humor about him. He seems like a guy who, although he's so powerful and can do these incredible things, he keeps thing very light. Especially on the show; the dynamic between Ronnie and Caitlin -- he's kind of the only one that can bring her out of her shell, and I feel like he can do that with a lot of people. He can make them feel very comfortable. He's just kind of a goofy, hammer-and-nails kind of guy. I feel like he's somebody that you would just want to be friends with -- which may be weird for a comic book character, but I don't think he takes things too seriously. You definitely see a little bit of that in my first episode, but later on there's a more serious side of things the first time they find Firestorm, rather than finding Ronnie Raymond. Since the accident, things have changed, and he's almost a shell of who he was -- but I'm sure it will go back to the lighter side of things when the Martin Stein dynamic comes into play.

On that note, "The Flash" has gotten a lot of notice and a warm reception from people thus far because it doesn't take itself as gravely seriously as a lot of comic book adaptations we've seen, and definitely has a palpable sense of fun about it. How much do you enjoy that aspect?

I think "Arrow" works really well at being the grounded, dark comic book show on The CW. I don't think "The Flash" would necessarily have been as successful as it is if it tried to live in that area. I think "The Flash" does feel more fantastic. It's a little more fantasy. There are a lot more superpowers involved than over in "Arrow." I think it does need to be a little bit of a lighter fare. I think both shows are very well done, and then the crossover episodes -- it'll be interesting to see how they do that. From what I saw in the pilot, the scenes between Stephen and Grant are pretty awesome.

And "The Flash" is really not shying away from showing superpowers in full force, which is certainly significant to your character. Firestorm, in the comics, has some unique abilities and is certainly very powerful -- what are you looking forward to in playing up that aspect of the role?

[Tonight], you get to meet Ronnie Raymond, but in December, you get to meet Firestorm. I went into the writers' room after reading the script before I left for Vancouver, and I was like, "Are you sure you want to do this? You're making him powerful right now!" They're like, "Oh yeah, we know." "Alright, cool!" I do some stuff in my first episode as Firestorm that is -- there's no holding back. Firestorm is powerful.

"Not holding back" seems to be a recurring theme with the show, and another addition is Victor Garber, who will be playing Professor Stein, the other half of the Firestorm equation. Have you been working with him much so far?

I haven't shot anything with Victor yet, but we did a TV movie together a couple years ago ["The Hunters"], and we had a blast shooting for a month in Vancouver. He was a great guy, we got along really well. I'm a huge fan of his work. I think this is going to be rad -- I get to not only work alongside Victor Garber, but I get to do a Victor Garber impression, because sometimes Firestorm is Ronnie, sometimes it's Martin Stein, but physically, it's going to be me when the two of us are inside my head. So that's another thing I'm excited for -- getting to play up the comedy of two people inside one guy's head.

That's definitely fortuitous the two of you have that shared history together.

I know. I've got to take him out for a drink or something, and figure out some mannerisms. [Laughs]

When it was announced back in July that you were going to be joining the show, people were excited about you and your cousin acting in the same fictional world. Are you hoping that you and Stephen get some scenes together at some point down the road?

I am. My first episode as Firestorm, I might not be the only Amell in that episode. But I really would love to have some actual scenes opposite Stephen, opposite Arrow. Maybe he'll need some help, and he'll need to call on Firestorm. I mean, I could get there pretty quickly -- I'm a superhero!

Is there an indication of how many episodes you're signed on for at this point, or is it an open-ended recurring role at this point?

It's exactly that. As soon as they're announced for the back nine, which I'm sure they will be soon because they're breaking records in ratings, they'll figure out a little more, but as of right now, I'm just back and forth to Vancouver, shooting whenever they need me.

Robbie Amell's debut on "The Flash" as Ronnie Raymond, "Things You Can't Outrun," airs 8 p.m. tonight on The CW.