Don't go to the Human Society and adopt a pet and expect that pet to be like Lassie. It has been emotionally abused and will not be able to shake out it. That animal will bite whenever it gets a chance. It won't suddenly wake up and appreciate it's now surrounding.
Don't try to love someone who's been abused emotionally, ethically, or physically. It's the same thing with a person. Unless they are really over the past and have actually forgive those that have hurt them. You will get shock, especially to find out that they also have learned helplessness and keeps going back to the ones that have hurt them, in spite of your contribution to their life.
Sorry, we are part of the animal kingdom, and it's an animal emotional reflex.