Alina Cojocaru and Ángel Corella in “Giselle.” Photograph by Gene Schiavone

A product of the Romantic Era, Giselle is supposed to be a ballet about uncontrollable passion. Originally choreographed for the Paris Opéra Ballet in 1841 by Jean Corelli and Jules Perrot, and set to a score by Adolphe Adam, the ballet hinges on Giselle’s two great loves — Albrecht and her dancing — and how both transcend even death.

Despite this, when watching my first Giselle last year at American Ballet Theatre, I was surprised by my tepid response to the work. (Whether this should be blamed on that evening’s casting or my own resistance to story ballets at the time remains uncertain.) The second act, in which Giselle protects Albrecht from the Wilis until the dawn saves him, struck me as perplexing and improbable. Why should Giselle show this cad such compassion, when his duplicity provoked her death?

Seeing the ballet again this year at ABT, fortunately, yielded a far richer return. Nuanced performances by two of the ballet’s leading interpreters, Alina Cojocaru (a guest artist from the Royal Ballet) and Natalia Osipova (a joint principal with St. Petersburg’s Mikhailovsky Theatre), revealed Giselle’s intensity and its tragedy. It was astounding to watch both women succeed by employing such distinct approaches.

With her small stature and childlike features, Cojocaru has the added advantage of looking the part of an innocent, vulnerable girl. Her unforgettable portrayal of Aurora in ABT’s The Sleeping Beauty last year showed her exceptional talent for capturing youth, but Giselle is an entirely different character. In her slumber, Aurora largely escapes physical and psychological pain, and emerges unscathed at the ballet’s end; Giselle, on the other hand, suffers at length, and to portray her requires more acting skill.

In the first act, Cojocaru shows these talents in abundance. She and her Albrecht, Ángel Corella, bound past each other in a flirtatious game of cat and mouse, and when Corella abruptly raises his arm to form a barrier, Cojocaru’s effusiveness disappears and she wilts. In this performance, one never doubts that Albrecht has complete control over Giselle. Cojocaru’s mad scene, a tour de force of dance and mime, is nothing short of devastating. As the orchestra plays a tune from a happier time, Cojocaru gives a heartbreaking smile, and her feet move, recalling her earlier duet with Corella. Then reality sets in, and her gentle features twist into anguish and despair before she collapses and dies.

Watching Cojocaru it can be difficult to determine where acting ends and dancing begins, as both spring from one well devised character. Her buoyancy as she skips in circles, her leg’s gentle sweep into grand battements: These qualities in her dancing suggest uncorrupted innocence, and Cojocaru’s impressive line furthers the sense of purity. Her dancing also changes remarkably in the second act, after Giselle enters the spirit realm. Her style becomes noticeably more fluid. She clings to the air during her jétés, and her supple arm movements complement the illusion of flight.

Natalia Osipova and David Hallberg in “Giselle.” Photograph by Gene Schiavone

Dancing the title role at a Saturday matinee, Osipova, known for her exuberant stage presence and almost impossibly high jumps, also played to her strengths. (“There’s nothing understated about her Giselle,” a friend remarked accurately.) If Cojocaru shows the innocence and vulnerability of youth, Osipova demonstrates its fire, and it proves crushing to see the flame extinguished.

Osipova’s uncommon projection of every step underscores Giselle’s love for dancing. Nowhere is this clearer than in her first act variation, when she devours space during a ring of pirouettes around the stage. Her energy also puts a triumphant spin on her second act entrance, after Giselle is summoned by Myrtha to join the Wilis. Hopping in circles in arabesque at dizzying speed, Giselle springs to new life. It’s reassuring, in a way, to know that death hasn’t put a stop to her dancing.

Her choices as an actress, too, diverge from Cojocaru’s. For instance, she makes it more obvious that Giselle’s mother isn’t alone in having reservations about Albrecht: Just moments after dancing gleefully with Albrecht, Osipova pauses in intense introspection.

As it turned out, the most memorable moment in that performance — and the one that finally instilled in me a deep appreciation for Giselle — belonged not to the ballet’s heroine but to Albrecht. At the height of his forced dancing frenzy in the second act, Hallberg launches into a series of 24 entrechats. He executes this formidable task with remarkable nobility, rendering it an act of pure devotion. Albrecht may be a philanderer, but the ballet holds real power when one has little choice but to believe in his love.