He began using drugs as a child. Heroin, by his account, was part of his life before he was a teenager. He has described being introduced to marijuana at age eight, through a family member. The overdose on heroin that he survived as a child — documented in his memoir and in biographical interviews — is the kind of biographical detail that has been partly processed by the decades of public storytelling he has done about his own life, transformed from something raw into something he can narrate with a degree of remove. It was not narratable at the time. It was simply what was happening to a child in Pacoima.
He was expelled from schools. He was placed in juvenile facilities. He engaged in carjackings, armed robberies, drug dealing — the specific crimes are documented in various accounts across his career, most thoroughly in his memoir. By the time he was entering young adulthood, he had a history with the California criminal justice system that was already extensive and that was pointing him, as clearly as a life can point toward anything, toward a serious adult criminal career.
His uncle Gilbert, the boxer, gave him a skill. It was the wrong application of the skill — Trejo has described his uncle teaching him to fight and then putting him in situations where fighting was the tool — but the skill itself turned out to matter later. In the California prison system, being able to fight had value. It earned a kind of status. It also, eventually, became the thing that gave him a way into a completely different life.