Character Analysis
As a simultaneous prelude and aside, there's a doctor in nearly every Chekhov, and a fair bunch in his stories, too. Chekhov himself was trained as a doctor, and starting writing short, funny stories to pay the bills. Who woulda thunk he'd end up better known for his (usually) depressing works of theater?
So, Chebutykin is the doctor in The Three Sisters. He's in his sixties, an old friend of the family who was once in love with Mrs. Prozorov. He sees her image in Irina and often embarrasses the young woman with shows of affection and inappropriate gifts. But don't worry, he sees her more as the daughter he wishes he'd had than as anything we'd think of as creepy.
Anyway, Chebutykin rents a room at the Prozorov house, frequently forgets to pay his rent, and after a long dry spell returns to alcoholism. It is Russia, after all. Beginning the play cheerful and happy at Irina's birthday, he dips into depression by the middle, and then recovers just before departing in Act IV. His most affecting scene comes as he roars into the girls' room upstairs, sloshed and upset: "The hell with 'em all," he says. "They think I'm a doctor and I know how to cure people, but I don't know anything. I forgot everything I knew, I don't remember a thing. Not a thing" (3.37).
While his need to get drunk implies a more sensitive nature than he admits (he's got to be trying to forget something), he willfully detaches from life. The doctor's favorite conversation starter—besides claiming his own ignorance—is the meaninglessness of life. "What difference does it make?" he says again and again, especially in the last act.