What Kaley Cuoco's Relationship With Her Sister Briana Is Really Like

Kaley Cuoco is the main force behind "The Flight Attendant," acting not only as its main star, but also as its executive producer. But "The Big Bang Theory" alum isn't the only Cuoco involved in the HBO Max series. In Season 2, fans were introduced to Cecilia, an associate of Miranda Croft. If the audience hadn't made the connection based on the resemblance, Cecilia is portrayed by Kaley's sister, Briana Cuoco.

Though viewers might be tempted to chalk it up to a classic case of nepotism, Kaley had nothing to do with the casting of the younger Cuoco. "No one told me she was auditioning ... I went to my Cecilia file, and I was watching everybody, and Bree popped up" Kaley told Collider. After learning about it, Kaley removed herself from the character's casting process, she added. "The studio approved her, the network loved her, and she got the job really totally on her own and made it her own," she added.

"The Flight Attendant" isn't the first project the Cuoco sisters work on together. Briana also has a supporting role on the HBO Max animated series "Harley Quinn" as the voice of Batgirl, which is why Batgirl and Harley Quinn, voiced by Kaley, have such a close bond, according to Screen Rant. In addition to acting, Briana is also a singer, having appeared on the fifth season of "The Voice," according to Deadline. Briana and Kaley clearly have a great professional relationship. And their personal bond isn't any different.

Kaley Cuoco experienced plenty of professional success in 2021. But, in her personal life, the Emmy-nominated actor was struggling. Kaley's split from Karl Cook hit her hard, she said on "The Kelly Clarkson Show" in April. "I wanted to be very upfront that it wasn't my best year, and I've been very sad," she admitted. Kaley's friendship with Zosia Mamet, her co-star in "The Flight Attendant," was crucial during those difficult months.

But Mamet wasn't the only person who played a key role in guiding Kaley through the rough waters of her divorce. "My sister ... would text me every morning to say everything's going to be okay," Kaley told Glamour in April. "Some mornings it was not okay, and other mornings I'd be like, 'Oh, my God, she's right, it's going to be okay.'" It wasn't the first time Kaley turned to her little sister for support, either.

Amid Kaley's divorce from her first husband, Ryan Sweeting, Briana was also her emotional rock. "As long as you're there for that person and they know you're going to be there without judgment and you can be just a good sounding board, that's all you can do for someone," Briana told Entertainment Tonight in January 2016, just a few months before the divorce was finalized. When times get rough, Briana knows how to take her sister's mind off things. "All we're doing, really, is watching 'The Bachelor,'" Briana added. "It's consuming our lives."

Briana Cuoco isn't just an actor and singer. Kaley Cuoco's sister is also a professional dancer and choreographer, skillsets that she often took advantage of. When Kaley staged the viral 2012 flash mob that saw "The Big Bang Theory" crew members show off their moves to Carly Rae Jepsen's "Call Me Maybe," Kaley turned to her sister for help with the dance, according to The Hollywood Reporter.

Flash mobs became a tradition on the set of the hit show, and Briana continued to be the woman behind the choreography, until the series finale in 2019, when the stars danced to the Backstreet Boys' "Larger Than Life," People reported. "Thank you @bricuoco @mandykorpinen @elizabethpetrin for choreographing this epic dance and for my crew who rehearsed for months and listened to me yap on and on about this endlessly!" Kaley shared on Instagram, according to the magazine. "It was worth it! Enjoy!!!"

Whether its through dance or acting, the sisters share a deep bond in front of and behind the cameras. Both consider themselves lucky to have the other to lean on. "Having my sister around, because she's my favorite person, has been a dream to be able to work with her," Kaley told Glamour about Briana's role in "The Flight Attendant." And Briana often uses her social media to express her love for Kaley. "Don't know what i'd do in this life without us going through it together," Briana captioned a December post.