Who is The Patient's fiance from The Screwtape Letters and what is their importance?

The patient's fiance is particularly offensive to Screwtape. He hates her. While his attitude toward the male "patient" is detached and methodical, Screwtape's passions are provoked by his fiance. Because of this, we come to understand that she is an extraordinarily good person.

Screwtape is angered by the fiance's innocence. She has a great sense of humor, she is intelligent, and she is attractive. She is also charitable and kind, traits that lead Screwtape to assure the reader that she is just the type which, in the early days of Christianity, would have been martyred for her faith with a smile on her face.