Who is Allie McDonald from Mercy and what is their importance?

Allie is a simple, small town girl. Allie has been in love with Cam since she was in high school, and her marriage to him is a dream come true. Convinced that Cam will some day wake up and realize he made a mistake, Allie spends her every waking minute trying to make Cam happy. Allie anticipates Cam's every need before he even knows what he needs. However, when Jamie comes to town Allie begins to realize what can happen in a relationship that is not equal. Allie sees that Jamie loved Maggie more than she loved him and in this Allie sees herself and Cam.