the flash season 2 firestorm previewIf you've seen trailers for Tuesday's all new episode of The CW's "The Flash," then you already know the flame-spewing superhero Firestorm is getting a sizzling makeover.

When Dr. Martin Stein (Victor Garber) falls ill, Barry Allen (Grant Gustin) and his S.T.A.R. Labs scientists must find a replacement for his metahuman partner Ronnie Raymond (Robbie Amell), who died last season saving the city.

After a screening of the flame-filled, emotionally charged episode -– titled "The Fury of Firestorm" –- Moviefone spoke to "Flash" co-showrunner Andrew Kreisberg and star Arrow" crossover, and the return of everyone's favorite villain -– Grodd.

1. Firestorm 2.0 Will Be Hilarious

When Ronnie died saving Central City, he left behind a grieving bride in Snow and an incomplete superhero in Dr. Stein. This week, Stein's needs are more pressing as his health fails him and we learn he must "merge" with another metahuman to survive. Flash and friends sift through several candidates to replace Ronnie, including an ambitious scientist Henry Hewitt (Demore Barnes) and a former athlete Jefferson "Jax" Jackson (Franz Drameh).

Mild spoiler alert that has already been widely reported: Jax will win the job.

Dr. Stein and Jax have zero in common, but as Kreisberg explains, that's by design. Juxtaposing the "radically different" characters "leaves more room for comedy with the Firestorm character," he said. Now we can look forward to more quip-based humor from Firestorm, especially after the character migrates over to The CW's upcoming spinoff "DC's Legends of Tomorrow."

2. What Does Ronnie Getting Replaced Mean for Caitlin?

Dr. Snow is a focal point of Tuesday's episode because the search for a new Firestorm is essentially a quest to close the book on Ronnie. As sad as that sounds, Panabaker believes it could be an important step forward for her character.

"What's especially hard for Caitlin, and maybe ultimately cathartic about this experience, is that she's connected to Stein and she cares deeply about him because he is her last connection to Ronnie," she explained. "So she's particularly invested in taking care of Stein... and making sure his next partner is... just as good if not better than Ronnie."

"This was really the episode where [Caitlin] kind of dealt with [Ronnie's death]. She can grieve through wanting to protect her dead husband's co-superhero," Kreisberg added. "This episode makes me cry."

3. Does This Have Anything to Do With Her Killer Frost Transition?

Panabaker owned the Internet last week after The CW revealed the first image of her playing the villain Killer Frost. But clearly something has to happen for Dr. Snow to become a cold-hearted baddie, because right now she's one of "The Flash's" warmest characters (all puns intended).

So, will she suffer another tragedy? Is Killer Frost actually Caitlin Snow's doppelganger from the alternate universe that has come into play this season? Universe? Or is there some other explanation? Kreisberg wouldn't say for certain, but he did imply that he and co-showrunner Greg Berlanti has been laying a foundation for Killer Frost's arc for quite some time:

"We knew we [the show was] going to be on for a few years, [so] we were able to play the slow con on some of these things," Kreisberg said. "It's only in hindsight that you look back and go, 'Oh, that thing in episode whatever from early Season 2, that tied into the thing that led into the other thing."

Hmmm. Mystery still unsolved.

4. Dr. Stein Gets a Weird 'Vibe' From Cisco

Last season Cisco Ramon (Carlos Valdez) was revealed to be Vibe, a metahuman who sees visions of alternate universes. He has been trying to hide his powers from Barry and Dr. Snow, but on Tuesday's episode Dr. Stein discovers his big secret and advises Cisco to share it with the group. But will he listen?

"[Cisco] has seen what happens to the other metahumans," Kreisberg said. "Good or bad intentions, they all go nuts and get locked up. So Cisco is really scared."

Furthermore, Cisco must deal with his disappointment over the nature of his vague powers: "It's not like he woke up and can fly," Kreisberg said. "So he feels like he drew the short straw. 'Barry gets super-speed, Ronnie gets to fly, and I get these blinding headache and nightmare visions of people being killed?' It's not, at first blush, the most heroic way to step into the world."

5. Looking Ahead... Is Jaytlin Really a Thing?

Dr. Snow's heart was broken after Ronnie sacrificed himself at the end of last season, but over six months have passed since his heroic death and already we're seeing signs that she may soon be ready to move on. We've seen sparks between her and newcomer/alternate universe Flash Jay Garrick (Teddy Sears) – could there be a legitimate romance in their future? All signs point to yes.

"Obviously there's something going on there," Kreisberg said.

Panabaker is shipping Jaytlin, too: "He's a fellow science nerd. What could be better for Caitlin?"

6. The Mother of All 'Arrow'/'Flash' Crossovers Is Coming

When "Arrow" and "The Flash" crossover this winter, they won't just be trading characters for a week, they'll be setting the stage for "Legends of Tomorrow."

Panabaker revealed that, because of the new show, this season's crossover episodes would be "exponentially bigger." Kreisberg agreed: "We looked back and thought those 'Flash'/'Arrow' episodes were the biggest things we'd ever done, but now we have more heroes, more villains, more mouths to feed – it's really exciting."

It won't just be the character pool that changes, either -– fans can also expect a shift in tone. "The 'Flash' episode plays more like an episode of 'Arrow,' and the 'Arrow' episode plays more like an episode of 'Flash,'" Kreisberg added.

7. Grodd's Return: Caitlin Will Be His Fay Wray

Gorilla Grodd, a fan favorite villain from "The Flash's" freshman season, is coming back this year in a big way. According to Kreisberg and Panabaker, the telepathic primate's return may inspire comparisons to the 1933 film "King Kong".

"Caitlin plays ['King Kong' starlet] Fay Wray to Grodd's Kong," he explained.

"[Grodd] has some unfinished business with her," Panabaker added.

8. The Big Regret Form Season One

"The Flash" scored big with both audiences and critics last season, but Kreisberg admitted there's still one thing he wishes he could go back and change: "The one thing we didn't do last year on ' The Flash,' and I keep kicking myself for it, is when Oliver got exposed as the Arrow. There was no mention of Flash for all those episodes about everything Oliver Queen was going through," he said. "For me, it's like they're all friends, they all know each other's secret identities, and they all care for each other – you'd think somebody would've said something about it."

However, this season the writers have been more vigilant about "honoring the fact that they're all in each other's life." "That's why we acknowledged Oliver's change into Green Arrow on 'The Flash,'" he said.

9. Batman Who?

Green Arrow and the Flash are a part of the Justice League, a crime-fighting super group that includes Superman, Wonder Woman, and Batman. DC Comics fans are naturally fond of speculating when and where those other big named heroes might rear their heads, but Kreisberg says the writers aren't focused on shoehorning them into their shows.

"We've gotten to do Green Arrow, Ra's al Ghul, the League of Assassins, Deathstroke, Flash, Killer Frost, and Vibe; now we're doing 'Legends' and Rip Hunter; we have Constantine coming on to 'Arrow'; and we have 'Supergirl.'" he said with a laugh. "So it's not like we're sitting there saying, 'God dammit, why won't they give us Batman?'"

In fact, he said the writers prefer developing lesser-known characters: "It's a lot more fun to show people that [viewers] haven't constantly seen."

"The Flash" airs Tuesdays at 8 p.m. on The CW.