Who is Soula from Waiting for Normal and what is their importance?

Soula owns the minimart across the street from Addie's trailer. Soula is a large woman with a wonderful sense of humor. She has been fighting breast cancer and eventually has 5 chemotherapy treatments for the disease. Soula knows that Addie's life is not an easy one and takes the girl under her wing. Soula enjoys having Addie around and it is clear that Addie brings joy into Soula's life.