'Bridgerton' star Luke Newton says the cast has a 'secret code' on how to survive being the main character

• "Bridgerton" star Luke Newton said the cast shares tips on surviving the spotlight each season.
• "We've now agreed that everything that goes from sibling to sibling is top secret," Newton said.
• Newton said he'll pass on his knowledge to whichever costar becomes the main character in season four.

The cast of "Bridgerton" is so tight-knit that they share confidential tips on how to survive the spotlight each season.

"We always talked about there being a book passed down through Bridgerton siblings," Luke Newton, who stars as Colin Bridgerton, said during an appearance on "The Tonight Show Starring Jimmy Fallon" on Wednesday. "And it never actually happened. It was all just through voice notes."

Netflix's TV show adaptation of Julia Quinn's book series focuses on the intertwined lives of eight Bridergton siblings. Like the novels, each season centers on a different sibling's love story.

Season one followed Daphne Bridgerton (Phoebe Dynevor) and Simon Basset (Regé-Jean Page) and season two focused on Anthony Bridgerton (Jonathan Bailey) and Kate Sharma (Simone Ashley). Season three, which recently concluded, showed Colin and Penelope Featherington's (Nicola Coughlan) friends-to-lovers romance.

During an appearance on the "Tonight Show" in May, Bailey spoke about each season's leads experiencing a new level of popularity, and the importance of staying grounded throughout the experience.

When it came to passing the torch to Newton for season three, Bailey said that his costar "didn't really need any advice, but I've been there on WhatsApp."

"And I will be for the siblings because we are bonded by this extraordinary thing," Bailey said.

Newton confirmed to Fallon that Bailey made himself available to share words of wisdom despite being busy juggling multiple TV and film projects. Season four is already in the works, but the leading Bridgerton sibling has yet to be officially announced.

"We've now agreed that everything that goes from sibling to sibling is top secret," Newton said. "It's like a Bridgerton secret. So now I will pass on to whoever the next sibling is going to be the secret code of how to survive it."