Onstage, Boston Ballet artist Sage Humphries is notable for her elegant poise and liquid grace. But offstage, she's a creative whirlwind: model, singer/songwriter and talented emerging choreographer. Amidst the demands of rehearsal and performance last fall, she choreographed her first major work, a deeply personal quintet set to original music by her brother Michael and showcased on Boston Ballet's BB@home: ChoreograpHER 2018. And this past May, the company asked her to create a new work for the music festival Boston Calling. Her White, commemorating the 50th anniversary of The Beatles' White Album, shared the festival spotlight with the likes of Tame Impala and Twenty One Pilots. "It was amazing to be part of that circle of artists who already had a huge fan base," she recalls. "The fact that Boston Ballet could be amongst that and get people excited about the art form was so special."