You're right about that, money always means competition. Sofia is characterized that way to show that it's not right for women to settle being treated like that. In the men's eyes she's seen as disobedient, but to everyone else, she's seen as a women who is taking a stand for herself, because back then, not many women did. I also think she's characterized like that to maybe guide Celie to be more strong for herself.

Anyways moving on..

Celie discovered that Mr.____ had been taking all of the letters that Nettie, Celie's sister had been writing to her and keeping them hidden from Celie. Up until this point, Celie was sure that Nettie was dead because she never heard from her. In the letters Nettie was telling Celie how she needs to get away Mr.___ because he had tried to make a pass at Nettie and she refused and because she refused Mr.___ told her that Celie would never hear from her. Anways..in her letters Nettie described how she went to Africa and then New York. Hopefully they will soon be reunited..we'll find out..