The victims, aged nine and 11, were tortured and sexually humiliated by two brothers aged ten and 11 in Edlington, South Yorkshire.
Revelations of how social services and other organisations missed numerous opportunities to intervene with the perpetrators during their violent upbringing has provoked widespread anger.
The mother of the older victim said: "Why did it take until they tried to kill (the two boys] for them (the authorities] to do something?
"They'd assaulted kids where they'd lived before, they shouted at a woman with five kids and punched the woman. The police did nothing. They threatened a teacher with a baseball bat."
The family plan to consult a solicitor to seek advice on suing for negligence. The boy's mother said agencies had "passed the buck".
The Conservatives have urged the government to publish the Serious Case Review in full so that lessons can be learned.