When I got married, my husband had a cat. She loved her owner, but hated me. She did everything she could to chase me out of the house. When I got near my husband, she would try to attack me by biting me. She would hiss all the time. It took about 6 months before she accepted me into her life. What I ended up doing was talk to her softly, but not touching her. I wanted to reassure I wasn't there to harm her or take away the love of her life. One day out of the clear, I went into the bathroom and she followed me. The next thing I knew, she was rubbing up against my leg, as if to say, you're ok. After that we were the best friends. So please give this cat you brought into your home some time to adjust. It won't happen over night, it could take some time.
