Biddy is a perfect contrast to both Estella and Pip.  She is a patient, sweet, kind, simple girl who is completely happy with her social status.

Like Pip, Biddy is an orphan.  Unlike Pip, she does not care about money or social status.  Although on Sundays she is perfectly “elaborated,” most of the time her “hair always wanted brushing, her hands always wanted washing, and her shoes always wanted mending and pulling up at heel” (ch 7, p. 31).  This indicates that she is not vain, and she only cares about her appearance when she is supposed to be making an appearance.

Biddy, who is “the most obliging of girls,” patiently teaches Pip how to read (ch 10, p. 51).  She seems to care for him, and she is essentially his best (or only) friend.

I reposed complete confidence in no one but Biddy: but I told poor Biddy everything. Why it came natural for me to do so, and why Biddy had a deep concern in everything I told her, I did not know then, though I think I know now. (ch 12, p. 67)

When Mrs. Joe is attacked, Biddy comes to help out.  She arrives with nothing but a “small speckled box containing the whole of her worldly effects” (ch 16, p. 86).

Biddy begins to be “improved” by being at Joe’s house.  Pip notices that she is “common” and can’t be like Estella, but she is “pleasant and wholesome and sweet-tempered” (ch 17, p. 88).  When Pip says he wants to be a gentleman, Biddy disagrees.

“Oh, I wouldn't, if I was you!” she returned. “I don't think it would answer.” (ch 17, p. 89)

When Pip tells her he could never be comfortable in his common life, she is sad for him and says it’s a pity.  She is happy at the forge with Joe, and annoyed when Pip suggest she help him on by teaching him manners.