Complex sentence: Her mother arrived and at first, saw Rachel as she was when she was a little girl, but when she saw the thorny vines on her body, she ran away, saying that the devil had taken her over.
Split into simpler sentences: Her mother arrived, and at first, saw Rachel as she was when she was a little girl. When she saw her with thorny vines on her body, she ran away, saying that the devil had taken her over.