Marija Berczynskas is Ona's cousin. She is much, much tougher than Ona. In fact, she joins the party leaving Lithuania and going to America because she beat the tar out of her former employer, a guy who raised her from childhood and who hit her regularly. Marija is not nearly as sensitive as Ona, which means that she lives longer. Still, Packingtown brings her down in the end.
When Marija first arrives in the States, she goes to pretty much every employer in Packingtown looking for a place to work. Her energy winds up getting her a job painting advertisements on canned meat labels. This is skilled work, and she makes a fair amount of money. Her energy also winds up getting her a boyfriend: Tamoszius Kuszleika, factory worker by day and violinist by night. This relationship inspires one of the very, very rare grains of humor in this novel. Apparently, everyone finds it hilarious that Marija is so much bigger than her pint-sized fiancé:
Everybody laughed at them, for Tamoszius was petite and frail, and Marija could have picked him up and carried him off under one arm. But perhaps that was why she fascinated him; the sheer volume of Marija's energy was overwhelming. (8.2)
All of these jokes about Marija's size and strength underline that she is a survivor, like Jurgis. Indeed, in many ways, Marija is a female Jurgis: she is young, strong, naive, and filled with rugged hope for the future.
Of course, the system is as stacked against Marija as it is against Jurgis. The canning factory closes down for the winter and she is completely desperate for work to help pay their rent. Her marriage to Tamoszius Kuszleika keeps getting put off and put off until Marija's family is in better financial shape (which never happens). Finally, Marija gets a job as a beef-trimmer, which means that she has to use a knife to trim the fat off cattle carcasses. This knife work is so fast that people often get injured. Of course, the knives are dirty because they are used to slash cattle carcasses all day. So, because no one catches a break in The Jungle, Marija's knife slips and she cuts her hand badly. The cut becomes infected and she almost loses her hand. All of this goes down while Jurgis is in jail, so the family has no steady income to rely on while Marija recovers. Teta Elzbieta, the children, and Marija are all evicted from their home.
After Ona and Baby Antanas die and Jurgis goes off hoboing, Marija steps up as best she can. There is one thing that a woman can do in Packingtown that a man can't (at least, according to Upton Sinclair; this may not be entirely historically accurate). Marija becomes a prostitute. She earns enough money to keep Teta Elzbieta's kids in school. She also develops a drug habit to cope with the depression of her job. Marija becomes incredibly pragmatic. When she sees Jurgis pre-socialism, but after Ona and Baby Antanas have died, Marija tells Jurgis they should just all have lived off Ona from the beginning. If Ona had just become a prostitute straight away, none of this sadness would have happened.
When Jurgis finally comes back to Packingtown, becomes a socialist and gets a job, he tries to get Marija to quit being a prostitute. But even though Marija started the novel with endless energy, she has now been totally broken down. Marija tells Jurgis that, once a woman becomes a prostitute, there is no point in trying to leave it behind – someone would figure out her secret eventually. She adds: "And besides [...] I can't do anything. I'm no good – I take dope" (31.2). For Sinclair, Marija serves as proof of what happens to young, energetic people in Packingtown who don't become socialists: they give in to despair. The terrible thing about the individualism of the American economic system (according to The Jungle) is that, when bad stuff happens, workers are trained to believe it is their fault. Even though Marija is as much a victim of the system as Jurgis is, she blames herself instead of the injustice of the business world that has ruined her life.