Who is Peiqin from Death of a Red Heroine and what is their importance?

Yu's wife, Peiqin, loves her husband very dearly and makes it a point to reassure him when he worries about her and their son. Peiqin is happy to put herself at risk to assist her husband and proves to be an adept agent when he needs her to pass information on to Chen. Chen sees Peiqin as the perfect wife.... loyal, intelligent, loving, and tranquil.