Billie Eilish is touring without her brother Finneas O'Connell for the first time

CNN
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According to her brother, producer and collaborator Finneas O'Connell, Billie Eilish has evolved from a teenage phenomenon into a full-fledged adult.

That's one reason O'Connell won't be joining his Grammy-winning little sister on her “Hit Me Hard and Soft” tour for the first time – except for a few tour dates – to support her on guitar, as he has done on each of their previous tours.

“There were a lot of years where I felt like I would never miss a show because Billie was, you know, 16 or 17 and I really felt like I had to be there every minute,” O'Connell said in an interview with Vogue Interview published on Tuesday.

“The truth is,” he added, “over the last few years of touring, she’s really grown up.”

Eilish's adulthood has manifested itself in what O'Connell described as the 22-year-old's “disciplined way of living on tour.”

“She sleeps all day to make sure she's rested for the show,” does hours of physical therapy and spends time warming up her voice to prepare, he added.

O'Connell announced Monday that he will be launching his album “For Cryin' Out Loud!” solo tour in February and released his latest solo album of the same name last week.

O'Connell and Eilish's parents, Maggie Baird and Patrick O'Connell, have also been an integral part of their previous tours, with Baird juggling everything from scheduling to making sure Eilish was fed, and the elder O'Connell served as a member of her stage crew.

“I'll get you tampons and cook you a burrito in no time, even if I have to use an iron,” Baird told Vogue on Tuesday's show.

And while Baird said she believes all artists can benefit from having a “mom on tour,” she and her husband will also be making themselves scarce this time around by letting Eilish go on a tour independently, according to her something like her college years.”

However, Eilish won't be alone. Indie rock duo (and actors) Nat and Alex Wolff, who Eilish told Vogue are among her best friends, are her opening act on the tour, which began late last month. She's also touring with her own live band for the first time and bringing some friends from her childhood with her.

“Hopefully,” Eilish told Vogue, “it will be the devil.” Fun.”