How Stuart Fails To Save The Universe Transforms Four Supporting Characters From The Big Bang Theory Into An Unlikely Band Of Heroes

Whether they were longtime fan favorites or later additions to the franchise, Kevin Sussman, Lauren Lapkus, Brian Posehn, and John Ross Bowie spent years stealing scenes on "The Big Bang Theory" without ever carrying the story.

In HBO Max's "Stuart Fails to Save the Universe," they're the ones in the spotlight.

As Stuart, Denise, Bert, and Kripke, the quartet suddenly finds itself at the center of the action, with Stuart tasked with restoring the universe to the version audiences spent 12 seasons watching on CBS — and the others becoming indispensable, despite being ill-prepared for a mission of this magnitude.

Along the way, the foursome tumbles through a series of alternate realities, encountering wildly different versions of familiar "Big Bang" characters as they race to undo the multiverse catastrophe Stuart accidentally unleashed.

As "Stuart Fails..." co-creator Zak Penn puts it, "These are the wrong people to be in this show. That's the point."

His fellow co-creator Bill Prady — who also co-created "Big Bang" with Chuck Lorre — says the key to striking the right tone was never changing the characters themselves. "The fun of it is that they continue to behave exactly as they behaved on 'Big Bang Theory,'" he explains.

Adds Penn: "They're having a conversation about developing a potion with a sorceress that can repair their time travel machine, but it sounds like a conversation from 'The Big Bang Theory,' and we do that a lot."

During TVLine's December set visit, Sussman, Lapkus, Posehn, and Bowie reflected on what it meant to return to characters they knew intimately — only to find themselves in circumstances unlike anything "The Big Bang Theory" ever demanded.

For Sussman, who appeared in 84 episodes of the original sitcom, the promotion represents the culmination of Stuart's increasingly tormented journey, which had just taken a turn for the better when he found love with Denise and the two moved in together — only for the series to end two episodes later. This time around, one of Stuart's biggest priorities is ensuring their relationship survives this multiversal odyssey.

"They only touched on the romantic aspect of Stuart and Denise in the original show, and now it's much more multi-dimensional," Sussman says. "It's more intimate, and it's funnier to see both of them in a way that you never did in the original."

For Lapkus, the spin-off allows Denise to emerge as a fully realized character in her own right — no longer the Comic Center's assistant manager or just Stuart's girlfriend, but an indispensable member of the team.

"It's really fun getting to play with these guys because they're all so funny, and finding my character amidst what they do has been helpful," she says. "How does she react to Bert? How does she react to Kripke? It's also very exciting to feel the relationship with her and Stuart develop and become more serious. Because with multi-cam, you only go so far, and so we're able to take things to another level."

Asked what Denise brings to the quartet, Lapkus says she's often the group's voice of reason. "I think it's providing a balance in a way — some grounded reality, because they're all kind of off in their own worlds," she says. "So I think I bring a little bit of, 'Let's walk in and figure out what's going on.'"

For Posehn, Bert's greatest strength is also his defining characteristic: "He's easygoing. We're in crazy situations on this show, and it just feels like the right way to play it. Because on 'Big Bang,' he felt unfazeable, and in this, there are a lot of things that should faze a normal person, you know? Where you'd go, 'Oh my God, what does that mean?' But I'm learning what his limits are."

Bowie, meanwhile, discovers what it means to be Kripke when he's more than just a thorn in Sheldon's side — "He's still awful and inappropriate, but you sort of get a cleaner idea of why he's awful and inappropriate" — while remaining every bit the antagonist fans remember from "Big Bang."

"There are a lot of moments for the character to shine," Bowie says. "Everyone has had a chance to step up — their moment with 'the cape' — and it's been really exciting to play that."

Ultimately, Penn says, the group's unlikely role in averting a multiverse Armageddon has a surprisingly simple endgame: "I always say to Chuck and Bill that the show is about whether they can get back to 'The Big Bang Theory.' Once they do, the show is over."

"Stuart Fails to Save the Universe" premieres Thursday, July 23 at 9 p.m. on HBO Max.