Character Analysis
Mamie is the pride of Woollett—the prettiest, smartest, and nicest girl that anyone in that little town has ever seen. Sarah brings Mamie along on her trip to Paris to use her as bait to lure Chad back home. The Newsome family pretty desperately wants Chad to move back to Woollett, marry Mamie, and settle down to run the family business. No one, though, ever thinks to ask Mamie what she makes of all these plans.
As the novel unfolds, we find out about Mamie that she once had feelings for Chad, but now she kind of hates his guts. The reason for this, Strether tells us, is that "she came over [to Europe] with ideas. Those she had got at home […] She was to save our friend" (10.1.58). In other words, Mamie thought of herself as the woman who could "save" Chad from a terrible life and change him into a dignified man. Yeah, the whole women-molding-men theme again.
The problem is that as soon as she gets to Paris, she realizes that another woman (Madame de Vionnet) has already done this. Mamie can never be with Chad now, because she would never be able to bear the fact that another woman could take credit for his wonderful change.
Throughout the early parts of this novel, Mamie is talked about like she's just a pretty face to lure Chad home—at one point Strether superficially shouts to Miss Gostrey, "Mamie will save him!" (2.1.217). Once we actually meet her, though, we realize that Mamie is a complicated person who doesn't necessarily share the same prejudices as Sarah Pocock and Mrs. Newsome: "She saw herself, everything, but she knew what she didn't want, and that it was that had helped her" (9.2.7). She is able to judge things for herself and is able to recognize the positive changes in Chad.
And this depth of vision makes her a pretty darn good person as far as Henry's James characters go.
Mamie's Timeline