"But is a weak person really weak? It requires little psychological sensitivity to see the so-called weak person puts all the strong people around him in his service. Weakness is one of the strongest means of rebellion, defiance, and demands. Regardless of how strong his opponents are, the weakling resists them, and makes them do his bidding rather than submit to theirs." Rudolf Dreikurs, Social Equality, Page 21
This probably could apply to children who learn how to use fear or being scared as a way to put a parent in his or her service or avoid cooperating. Any symptom such as ADHD, depression, anxiety, fear, and a host of other diagnosis including drugs and alcohol can be a way to control another. Symptoms can be used as weapons against another and a position of power, camouflage as weakness. You will know by your emotional reaction.