In John Updike's short story "Dear Alexandros," we can apply the characterization method to discern a lot about Alexandros and Mr. Bentley.
One element of characterization is speech.
We can discern that Alexandros is not as well-versed in English as Mr. Bentley based on the relative awkwardness of his letter. One example of Alexandros's unfamiliarity with English is when he writes, "I want to inquire about your good health, and then, if you ask me, tell you that I am keeping well."
As for Mr. Bentley, he’s fluent in English. Perhaps this is one reason why he's in a position to give Alexandros eight dollars a month. His mastery of English points to his privileged position. Meanwhile, Alexandros's clumsy English links to his less well-off place in the world.
Another element of characterization is physical action.
In Updike's short story, we might say that the main physical action is Mr. Bentley giving Alexandros $8 a month. This might lead us to think of Mr. Bentley as charitable. It might also bring us to characterize him as a bit of cheapskate. Mr. Bentley can afford to have homes in New York City and Greenwich, Connecticut. Both are expensive places to live. It doesn't seem unreasonable to conclude that Mr. Bentley could afford to give Alexandros more than $8.
We also see how their characterization develops via their beliefs and attitudes about family.
Alexandros tells Mr. Bentley about his "granny" and sister. Is Mr. Bentley surrounded by his family? No. He's separated from them. As he tells Alexandros, "Mrs. Bentley and I no longer live together." He also tells him how he's about to "take a young woman out to dinner."