"She finally breaks down and lets her opponent in," Fitzgerald said. "I say 'opponent' because she and Hank are fighting most of the time. Kate lets the audience in, too, by the end. You can't help but hate her, and you can't help but love her."
Keeping up all that emotional intensity, let alone all that choreography, takes a toll.
"You're working six days a week, with physical activity five hours a day," Fitzgerald said. "I take a ballet class every day, and a ballet warm-up before every show. Every other day, I do some yoga to keep everything stretched out so I don't injure myself. I have never been with a company so careful with how they use their bodies. There haven't been any injuries, nothing detrimental — just little things, like a hamstring pull."
Some of Tharp's routines help ease the strain — on Fitzgerald.
"The lifts in this show are insane," she said. "There are times when my feet don't touch the ground for long stretches."
In addition to repeating complicated choreography night after night, cast members have to hear the same songs, sung in exactly the same way by the same voice. Fortunately, Fitzgerald joined "Come Fly Away" already a committed Sinatra fan.
"My grandmother was a singer in a band, and she always played this music," she said. "And my family had Sinatra playing in the house when I was growing up."
Her family moved to Ellicott City from Albany, N.Y., when Fitzgerald was 5. The show-business bug bit early.
"The first time I saw 'Wizard of Oz,' I wanted to be Dorothy," she said. "I wanted to dance and sing. And I was obsessed with Ann-Margret when I was growing up. I played 'Bye Bye Birdie' and 'Viva Las Vegas' recordings every day for four years."
Fitzgerald graduated from Centennial High School, performed in plays with the Drama Learning Center and added to her early stage experiences at Toby's Dinner Theatre.
In addition to classes at the Ballet Royale Institute ("It's a very rigorous school"), Fitzgerald developed her dancing skills at summer camps offered by American Ballet Theatre and the Joffrey Ballet. After high school came the Boston Conservatory. She only stayed there a semester and a half, though — the chance to join the "Fosse" tour was too tempting.
Fitzgerald never did have her eye on "Swan Lake," anyway.
"I thought about classical ballet," she said, "but something in me could never stay in that line. I wanted to be more extravagant. Jazz and modern were always more my thing. But I couldn't be good at this if I had not studied ballet."
A dancer's body typically comes with a kind of sell-by date. Longevity onstage is not assured.
"I have a couple years left," said Fitzgerald said with a laugh. "I haven't made any plans to stop in the near future. I feel the best I've ever felt."
If you go
"Come Fly Away" runs this coming weekend, Friday through Sunday, at the Modell Performing Arts Center at the Lyric, 140 W. Mount Royal Ave. Tickets are $70.20 to $80.45. Call 410-547-7328 or go to tickemaster.com.