Ronald Fairbairn wrote a complete psychoanalytic model in a series of papers (1940, 1941, 1943, 1944)  which are collected in his 1952 text "Psychoanalytic Studies of the Personality".  His model explains the surprising psychological reality that abused children become deeply attached to their abusers. He saw that lack of love, chronic indifference and abuse led to a counter-intuitive emotional attachment to the very parent who was abusing them.  The child's unmet dependency needs from chronic emotional deprivation, as well as the complete lack of other human alternatives in their environment, leaves the child stuck at an earlier emotional age, as they have not been able to continue their developmental progress in the absence of parental help and support. Thus the child may be 12, but emotionally and developmentally they may experience the world like a six-year-old, as their increasingly developmental needs force them to focus on the abuser, waiting for any hint of developmental support. The child becomes concerned for the abuser's welfare because their developmental progress hinges upon on the whims, moods and emotional state of the abusive parent. In addition to the pressure from unmet developmental needs, the child is also aware of the potential danger that can emerge from the volatile and aggressive parent, and anything that they can do to placate, please or draw praise from the abuser increases their chance of survival.