Character Analysis
Masha is the middle Prozorov sister. If you've read The Seagull recently, you'll remember that it also features a Masha who wears black and is married to a dull-as-dishwater schoolteacher. Fun parallel, huh? Anyway, while Irina has the strongest arc in the play, Masha is often the favorite part for actresses. She's strong-willed, sharp-tongued, and reckless. More like a Katniss to Irina's New Girl.
The Educated Feline
Throughout the play, Masha whistles, hums, and sings a tune that references a Pushkin poem. Every Russian would've known the poem (Pushkin : Russia :: Shakespeare : the English-speaking world), so Chekhov doesn't bother to quote it in full. So what you've got to know is that the part he leaves out features an educated cat walking around in a circle—clearly how Masha thinks of herself.
But is that a good thing? This cat feels like she's, um, meowing up the wrong tree. She rues her over-education: "what's the point of knowing three languages in a town like this? It's a useless luxury. No, not even a luxury; it's an unnecessary appendage, like a sixth finger" (1.142). At least one of those languages lets her read poems by Pushkin.
The Cool Cat vs. Kulygin
Masha's respect for education at first drew her to Kulygin. "I got married when I was eighteen, and I was afraid of my husband because he was a teacher, and I was barely out of school. I used to think he was terribly wise, intelligent, and important. Now I've changed my mind" (2.31). And don't you forget it, ladies 'n gents.
By the time she's in her mid-twenties at the start of the play, Masha is constantly irritated by her husband's parochialism (small-town mentality), and she lets him know it. She's unwilling to attend his yawn-worthy teachers' parties and often tries to avoid him—especially when Vershinin comes to town.
Veering Toward Vershinin
She doesn't try to hide this affair. At all. Masha is attracted to Vershinin at first sight. He starts going on about how life in the future will be beautiful and suddenly Masha's all "I'm staying for lunch" (1.144). This guy clearly has a broader and at times more hopeful view of the world around him, and this is pretty refreshing for a lady as brilliant and bored as our Masha.
The most strong-willed and self-serving of the sisters, Masha carries on with Vershinin for years. Surely her sisters know what's up, but after the fire she says it straight out: "I'm in love… I love that man, the one you saw just now… Well, that's it: I love Vershinin" (3.107). When he departs with his unit, Masha sobs openly before her husband. Yep, that's not so subtle. But what can you do when your only speck of enjoyment marches off with the troops?
Timeline