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

Peiqin is Yu's wife. She loves her husband very deeply and takes pains to reassure Yu when he worries about her and their son. She is happy to put herself at risk to help her husband and proves to be quite an adept agent when Yu needs to covertly pass information to Chen. Chen sees in Peiqin a lot of the qualities he desires in a wife such as loyalty, intelligence, a loving nature and a tranquility that appeals to him, although he has no design on Peiqin herself.