As the youngest and most optimistic sister in the Prozorov family, Irina experiences the greatest character change. At the opening of the play Irina imagines a life filled with meaningful work. She hopes to fall in love and still believes happiness is possible, particularly if she returns to Moscow. Perhaps because of her optimism, many men in the play are in love with her. Solyoni and Tuzenbach come to duel for her affections, and Chebutykin loves her like a father. Through the hard lessons of life, however, Irina loses her youthful naïveté and comes to terms with life's disappointments after she realizes work leaves her unhappy, her romantic prospects are slim, and she will never return to Moscow. By the end of the play Irina has resigned herself to a spinster's fate after Solyoni kills Tuzenbach in the duel.
A classically trained musician, Masha misses Moscow culture perhaps more than any of the other sisters. Her longing leaves her prone to feeling "blue." As well as missing Moscow, Masha is unhappy in her marriage. She had hoped her educator husband would be intelligent and interesting, but she finds him dull. She has an affair with the philosophizing Vershinin that ends in heartbreak when the army battery moves away. Masha is the most emotional of the three sisters, openly weeping when Vershinin leaves. She is outwardly annoyed with her husband, despite his loyal affection.
As the eldest sister Olga is most pragmatic about her position. She works hard as a schoolteacher, taking on unwanted responsibilities to help support her family. A spinster, Olga never even entertains the idea of romance as the other sisters do. When Natasha threatens to fire Anfisa, Olga transfers the ancient woman into her new apartment. While she remains as dissatisfied with life at the closing of the play as she was in the beginning, her experiences cause her to question the meaning of suffering as in the closing line of the play, "If only we could know."
Vershinin's marriage to a deeply depressed woman who routinely tries to commit suicide has left him torn between marital responsibility and disillusionment with love. By focusing on the future he fights against the depression that has engulfed so many other characters. He regularly suggests that 200 years from now, current suffering will have produced great happiness. While those currently living will never experience that bliss, their work (their suffering) is important. As an army man Vershinin stays loyal to his post, moving away from the village with his family despite being in love with Masha.
Natasha's character in Three Sisters experiences the most transition as she rises from a shy, village girl to headmistress of the Prozorov household. When she and Andrey first meet, Natasha is so shy and embarrassed she runs away from the lunch table when the sisters tease her. After marrying Andrey, however, Natasha begins pushing the sisters around, taking over their bedrooms and eventually the whole house. She abuses the staff, manipulates the sisters, and is unfaithful to Andrey, yet when the play closes, she controls the house and a bulk of the family's money.
Baron Tuzenbach has a heart of gold. He's gentle, good natured, intelligent, and loving toward Irina, with whom he's been in love for five years. He is self-conscious about his privileged background and, like Irina, idealizes fulfilling work. Unfortunately, he's extremely unattractive. Irina hoped to fall in love with an exciting, handsome, artistic man, but her tiny village doesn't offer that option. Out of desperation she accepts Tuzenbach's proposal, even though she doesn't love him. Tuzenbach accepts that Irina will never love him but promises to continue loving her forever. Although Tuzenbach's career has been in the military, he leaves the forces to take up civilian work in the hopes of impressing Irina. He also agrees to duel with Solyoni for Irina's affections, even after she accepts his proposal. Tuzenbach is killed in the duel.
Like all the characters in the play, Chebutykin becomes disillusioned and depressed. Chebutykin knew the Prozorov family in Moscow and was in love with their mother (who is now dead), although it's unclear whether the romance was mutual. Chebutykin transfers his affections for the mother onto her daughters, particularly Irina. After accidentally killing a patient, however, Chebutykin becomes a depressed alcoholic who questions life's reality and meaning. He smashes the mother's porcelain clock to send the message that what one sees isn't always reality. At the end of the play he suggests nothing in life matters.