With her sparkling footwork, musicality and lustrous phrasing, Ms. Fairchild, 33, who makes her Odette-Odile debut on Sept. 26, is used to commanding the stage in effortless displays of virtuosity, especially in ballets by the company’s founding choreographer, George Balanchine, like “Donizetti Variations,” “Rubies” and “Tchaikovsky Pas de Deux.”
But her roles in full-length ballets have veered more toward “Sleeping Beauty” and “Coppélia” — parts, traditionally, for smaller dancers. (Ms. Fairchild is 5 feet 4 inches.) “One tends to typecast people,” Mr. Martins said in an interview. “You have your soubrettes, your tall dancers and so forth — you wouldn’t put her in ‘Diamonds,’ you would put her in ‘Rubies.’ That’s sort of historic here. Balanchine set the pace in that regard. On the other hand, every once in a while there are people who defy any category, and I think she’s one of those.”
Ms. Fairchild took a leave of absence from City Ballet in 2014 to perform as Ivy Smith in “On the Town” and returned to the company with her crisp technique intact — impressive and rare — while dancing with more exhilaration and daring than ever before. She’s even grown a half-inch. (She credits it to Pilates and Gyrotonics.)
That growth — in body and spirit — was apparent in the studio. At a recent “Swan Lake” rehearsal, Gonzalo Garcia, her Prince Siegfried, watched in fascination as she followed the suggestion of the ballet master Susan Hendl to think of her relevé — rising on her toes — as coming from her hip in arabesque.
“Wow,” Mr. Garcia said.
Ms. Fairchild shot him a look. “Really?”
“It’s not little Megan anymore,” he said. “It’s big Megan.”
But her groans, which gave way to bursts of dismayed laughter, also revealed what a challenge “Swan Lake” is. At one point, she announced, “I have to say this is my most unfavorite start to a variation.”
Watching and listening to Ms. Fairchild, 33, who strings sentences together as rapidly as an actress in a screwball comedy, was a window into her dancing as much as into her agile mind. (After 15 years, she earned a degree in mathematics and economics from…