In Ethan Frome what does the narrator learn about Frome from other characters?

The narrator essentially learns almost everything about the elusive Ethan Frome through other people in the town.  He is intensely curious about the unique man, and so asks a lot of questions.  He gets bits and pieces from several different townspeople--the grocer, Mrs. Ned Hale (who he is boarding with while he is in town), and Harmon Gow (who drives the narrator places in his cart).  From each person he gets a different little bit of information:  from the grocer, he learns that Ethan had a "smash-up" about 24 years ago that crippled him, from Gow he learns about Ethan's sickly parents and Zenobia, his sickly wife, and from Mrs. Hale he learns a few more details about Mattie, relating to why and how she came to stay at the Frome household.  So, he starts to piece together the foundation of Ethan's story through the other characters.

It isn't until the narrator visits Frome's household and sees both Zeena and Mattie in the house together that he really feels like he understands Ethan Frome.  It is at this point that the narrator has a "flashback," and Wharton goes back and tells the beginning of the story that we have missed, filling in all of the details that the townspeople haven't told him already.  I hope that those thoughts helped a bit; good luck!