Abusers use everyone and everything around them in a manipulative way, including using their children as tools of abuse.
The abuser often recruits his children to do his bidding. He uses them to tempt, convince, communicate, threaten, and otherwise manipulate his target, the children's other parent or a devoted relative (e.g., grandparents). He controls his - often gullible and unsuspecting - offspring exactly as he plans to control his ultimate prey. He employs the same mechanisms and devices. And he dumps his props unceremoniously when the job is done - which causes tremendous (and, typically, irreversible) emotional hurt.
Some offenders - mainly in patriarchal and misogynist societies - co-opt their children into aiding and abetting their abusive conduct. The couple's children are used as bargaining chips or leverage. They are instructed and encouraged by the abuser to shun the victim, criticize and disagree with her, withhold their love or affection, and inflict on her various forms of ambient abuse.
As I wrote in Abuse by Proxy:
"Even the victim's (children) are amenable to the considerable charm, persuasiveness, and manipulativeness of the abuser and to his impressive thespian skills. The abuser offers a plausible rendition of the events and interprets them to his favor. The victims are often on the verge of a nervous breakdown: harassed, unkempt, irritable, impatient, abrasive, and hysterical.
Confronted with this contrast between a polished, self-controlled, and suave abuser and his harried casualties - it is easy to reach the conclusion that the real victim is the abuser, or that both parties abuse each other equally. The prey's acts of self-defense, assertiveness, or insistence on her rights are interpreted as aggression, lability, or a mental health problem."
This is especially true with young - and, therefore vulnerable - offspring, particularly if they live with the abuser. They are frequently emotionally blackmailed by him ("If you want daddy to love you, do this or refrain from doing that"). They lack life experience and adult defenses against manipulation. They may be dependent on the abuser economically and they always resent the abused for breaking up the family, for being unable to fully cater to their needs (she has to work for a living), and for "cheating" on her ex with a new boyfriend or husband.
Co-opting The System
The abuser perverts the system - therapists, marriage counselors, mediators, court-appointed guardians, police officers, and judges. He uses them to pathologize the victim and to separate her from her sources of emotional sustenance - notably, from her children. The abuser seeks custody to pain his ex and punish her.
Abusers are insatiable and vindictive. They always feel deprived and unfairly treated. Some of them are paranoid and sadistic. If they fail to manipulate their common children into abandoning the other parent, they begin treat the kids as enemies. They are not above threatening the children, abducting them, abusing them (sexually, physically, or psychologically), or even outright harming them - in order to get back at the erstwhile partner or in order to make her do something.
Most victims attempt to present to their children a "balanced" picture of the relationship and of the abusive spouse. In a vain attempt to avoid the notorious (and controversial) Parental Alienation Syndrome (PAS), they do not besmirch the abusive parent and, on the contrary, encourage the semblance of a normal, functional, liaison. This is the wrong approach. Not only is it counterproductive - it sometimes proves outright dangerous.
This is the subject of the next article.