There is a wonderful description of these characters right here at eNotes.
Briefly, Dexter is a gullible young man who falls for the charms of and lively personality of the wrong woman. He is loyal and patient, but he does eventually realize that Judy is only playing with his affections.
Judy is the classic femme fatale, the girl whom every man desires. She flirts; she seduces; she toys with men's feelings and plays one against another. But she never seems to realize what she is doing. Her beauty and charm are her only assets, but she reveals much about her character when she says of herself, ‘‘I'm more beautiful than anybody else … why can't I be happy?’’
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