Showrunner Eric Wallace also reveals “one of the endgames of ‘Armageddon.'”

“The making of this was completely different from any other crossover we’ve had to do.”

It’s not safe."

The Flash

Grant Gustin and Brandon Routh on ‘The Flash’.Katie Yu/The CW

What if we spun off of that?’

It was originally going to be with a very different villain.

Dusting off that years-old idea was the easy part.

The Flash

Grant Gustin as Barry Allen and Tony Curran as Despero on ‘The Flash’.Colin Bentley/The CW

Thankfully, two pieces of pop culture held the answer.

The first was Matt Reeves' 2008 horror movieCloverfield.

It’s not about the monster.

The Flash

Grant Gustin as Barry Allen and Stephen Amell as Oliver Queen in the first Arrowverse crossover “Flash vs. Arrow”.Diyah Pera/The CW

It’s about the people on the ground and what they’re going through.

It’s a very, very emotional movie," says Wallace.

It’s big but that bigness isn’t always where the camera is focused on.

Arrow

Colin Bentley/The CW

The writers were also inspired by"Flash vs. “[Flash vs. Arrow was] just two dudes.

It’s Flash plus blank, and that became the new template.

(Here’s more information on Batwoman’s role in the story.)

The Flash

Katie Yu/The CW

“Shehasto be in this story because of what is being told.

It’s all intertwined.

For Wallace, it was important that these guest appearances weren’t just cameos.

“Every single guest star has their emotional journey that they go on.

There might be one exception, but it’s a pretty darn funny storyline.

There’s some real humor there,” says Wallace.

I realized we can’t do that.

We have to go back.

And that means less characters, but more screen time.”

According to Wallace, the visiting actors appreciated this approach.

You’re not just honoring what came before with my character’s journey.

She doesn’t, obviously, because we only have her for ‘Armageddon.’

“This is a season premiere ofThe Flash,” says Wallace.

But I loved it.

The Flashreturns Tuesday at 8 p.m. on the CW.