Mr. Roversi suggested that she cut it. Ms. Letissier, ambushed in the moment by latent insecurity, resisted. “My jaw is a bit square,” she murmured.

“Your jaw is square, that’s why it’s cool!” she recalled Mr. Roversi replying, undeterred, with infectious conviction. “Cut your hair and allow yourself to be exactly who you want to be!”

And so she did.

On her way to the train after the shoot, with short, slick hair that made her look like a boyish Chet Baker, she basked in her reflection in store windows. Passers-by turned their heads. “It was like Christmas,” she said. “I felt like, ‘This is how I want to exist.’”

FINDING NEW WAYS of existing is a specialty of Ms. Letissier’s. Over three interviews this summer, she seemed consistently at ease — hyper-articulate, with a born performer’s inclination to augment her speech with silly voices, or by breaking into song. But she spent most of her youth uncomfortable in her own skin. She found refuge in theater, but her body often felt like an ill-fitting costume. “I always wanted to be Romeo, not Juliet,” she said. “Romeo is a much cooler way to be — Juliet’s just up in a balcony, waiting.”

Uncertain of how to perform femininity in high school, she went through a phase in which she wore heavy makeup and frilly skirts, earning her the nickname Marie Antoinette. One of the first songs she ever wrote, “iT,” a spiritual prelude to “Chris” from “Chaleur Humaine,” is a Freudian fantasy about acquiring a penis and its privileges.

On the new album, Ms. Letissier, who described herself as gender-queer and pansexual, doesn’t seek to abandon her womanhood so much as expand its turf. In evolving the character of Chris, she looked to famous women who had drunk from the cup of male privilege before her, including Madonna, Janet Jackson and Sigourney Weaver, as well as one pretty boy: Leonardo DiCaprio, circa 1996 — Romeo himself.