Leopardino , a toxic or narcassist parent , does have scapegoat(s) and favorite(s).
They work on devide and conquer tacktics with thier children.
The also have to be seen to the outside world as nice people . Thats easier if only one of their children is the chosen "victim".
If 3 out of 4 children say that the parent is a good parent , then it must be the last childs fault .The last child /victim is always labeled a "problem child".
Toxic parents are highly skilled at being manipulative and sneakky. They get away with most of what they do because they are a good enough parent to only some of their children.
Im glad you dont understand toxic parents , because that means you have never had experience of one.