Who is Captain Everard from Tales of Henry James: The Texts of the Stories, the Author on His Craft, Background and Criticism and what is their importance?

Captain Everard appears in the story, In the Cage. He is a gentleman wand frequent customer at the post office. Over the course of the story, the operator falls in love with Everard. Whe he becomes aware of her feelings, he does his best to avoid her.