The ability of Pit Children to manipulate their half or step siblings can not be over stated.
In the example, Julie, who grew up with her mother, who had no issues, could be manipulated by her half brothers. Half brothers she never grew with who somehow were able to penetrate and manipulate her mind.
The reason this is possible is because persons with severe psychological problems can invest every atom of their being into destroying a relationship.
Normal people have a cornucopia of interests, ideas, involvements, so invest only a portion of themselves in each aspect.
The ‘Pit Child’ is fixated. The Pit Child can repeat and attack over and again without pause.
Where most people don’t have a reason to analyse a perfectly normal or ordinary life, the Pit Child can so focus on tiny events and incidents to create a fabrication, and sell it to the half sister/ brother.