I found this article fascinating and relevant, even though it appears to be from 1992 and concerns abused kids who kill the abuser.
https://www.paulmones.com/when-kids-kill-abusive-parents
"Typically, the child who kills a parent is from 16 to 18 years old, from a white middle-class family. Most have above-average intelligence, although their schoolwork may be below average. They generally are well-adjusted in school and the community, though they tend to be isolated, without many friends. They commonly have had no prior run-in with the law.
Abuse is a mild term for the torture that parents inflict.
Most abused children suffer quietly. The lucky ones find other supportive adults who nurture them, typically a nonabusive parent, grandparent, teacher or coach. Some manage to cope by emotionally numbing themselves or by taking out their repressed anger on someone other than the abuser. Others find the torment intolerable. They may run away or try to commit suicide. Donna Marie Wisener once had a gun in her mouth when she was discovered by her father, who told her, Next time do it right.
Some seek outside help, but often to no avail. I spent my whole childhood trying to get help, and none ever came, says Roy Rowe, 19, who last year was sentenced to four to 12 years for killing his stepfather. ... Teachers reported their suspicions of abuse; relatives tried to intervene. But each time, police officers and social workers left the children in the home. On his 17th birthday, Roy shot and killed his stepfather on their front porch as he came home from work.
What makes some children finally snap? They dont pay as you go with regard to aggression, observes Detroit psychiatrist Emanuel Tanay. You might think theyre passive, but theyre also explosive. Many parricides occur when the child is on the cusp of independence, about to break away from a parents domination. Sometimes the killing is triggered by a desire to protect the other parent or siblings.
Often an escalation in the level of violence precedes the slaying. Mark Martone was 16 when he shot his father to death. This was not a routine beating, he recalls. His father had slammed his head against a radiator, kicked him in the ribs and struck him on the skull with a hammer. As he sat in jail the night of the murder, Mark was still terrified. Oh, God, he said to himself, what am I doing here! Dads going to kill me! Mark was convicted of homicide as a juvenile but was sentenced to six months probation. Like others who have suffered the same ordeal, he remains torn by his immense relief, guilt, grief, even love. It may sound sick, but I did love him, says Mark. I still love him. I mean, he was my father.
Though some occur during an episode of brutal abuse, most happen when parents are in a vulnerable position: coming in the door, watching television, cooking dinner with their back turned, or sleeping. That may be the only time youngsters can overpower their abusers, but it makes the killing appear to be cold-blooded murder.
Many abused youngsters think that hitting and kicking are normal, and most cannot conceive of turning in their mothers and fathers."