Three years ago his father, Ciro, was killed in his orthodontist clinic by gunmen. Juan fled with his family and has not returned to their home town, Aguachica, in civil war-ravaged Cesar province. He does not know whether his father's assassins were Marxist guerrillas or paramilitaries, but the death threats continue.
"They killed him because he was a community leader in a hot zone," Juan said. "When armed groups want to make their presence felt ... they kill someone of influence."
Officials and neighbours had sought advice from his father, who helped with free health care for the poor. Juan's mother, unqualified for any job, sold their car and became a street vendor. Juan was 15.
They have been living rough ever since, continually on the run. If they are lucky they lodge with distant relatives, though they do not want to endanger their hosts. Staying with close relatives is too risky.
But Juan would not indulge in self-pity. "There are children ... whose whole family has been massacred," he said.
He remembers a young father, infant son in his arms, who was ordered at gunpoint to place the baby on the ground. Before the bullets struck him, the final sound the man heard was his son's wails.
Atrocities are standard ways of intimidating civilians and driving them off useful property. A group painting by young children uprooted from Turbo village last year includes red slashes and a river clogged with armless bodies, like the ones they saw hurled into the rapids by their attackers.
Small towns such as Aguachica are particularly vulnerable. Civilians get caught in the crossfire and are often targeted. Mutilation is common, and brutalised adolescents joke about it. Some come to commit such atrocities themselves.
"Gunmen arrive at your house and say, `Feed 60 men'. Or they go to a farm and kill a cow for the group to eat. You must be the host. So if you are obliged to help the guerrillas, you become the enemy of the paramilitaries; if you help the paramilitaries, you're an enemy of the guerrilla. You are between the sword and the wall," Juan said.
Lest they be labelled collaborators, even poor farmers hesitate to sell a chicken to a stranger and offering water to a passer-by is unwise. Villagers must take sides or run. Migrations, with as many as 4,000 people forced out of strategic territory before army operations, are common. Officials reckon that for every massacre a thousand people become displaced.
After four decades of bloodshed in Colombia there are 1.5 million internal refugees, mostly women and children. If they seek sanctuary in big cities such as Medellin, there are new sorts of outlaws to fear: gang members, drug lords and death squads that take pride in spraying the homeless with bullets to further "social cleansing". An experiment restricting press photos or video footage of the civil war carnage to black and white was recently abandoned after it appeared to make no difference in children's attitudes to the everyday slaughter. They are blase about blood.
Children who often bolt from their ruptured family homes after being mistreated volunteer to join the rebels or the militias. The security forces recruit boys as young as 15, and girls are plentiful in the Revolutionary Armed Forces of Colombia.
Some risk being poisoned following fumigation by anti-drug planes when have to harvest coca or poppy, which will be sold to buy weapons.
Beatriz Linares, a rights activist, attributes the high recruitment rate to how little access there is to school or recreation. "These children don't know how to use their free time. In these armed groups they find affection. They are given guns and for once in their lives feel useful. They don't understand the risk. They have no fear of anything."
Typically, children as young as eight become spies or messengers for the paramilitaries, while minelayers for the rebels average about 14. Others are put in front ranks to draw fire. If captured, these militants are sent to juvenile prison. Deserters are also jailed, regardless of age.
Pubescent boys not at school face conscription by right and left and abduction is rife. Colombia had 2,600 kidnappings last year alone. Children are easy to snatch and cheap hostages to feed.
While the government attempts to pressure displaced families into returning home, few comply, because there is no assurance of security. Repeated attacks, abductions, and extortion are genuine dangers.
Children in Colombia seem to have two grim choices: they accept their vulnerability to violence as inevitable, or engage in the violence themselves.
Yet in October, 15 million Colombians took to the streets with small white flags, demanding peace. Given the brutality of the past, they are desperate for a future.
THE COLOMBIA FILE
n There are 30,000 armed juveniles (under-18s) in the country.
n Of these, 18% have killed at least once; 40% have fired at someone; 60% have seen someone killed; 78% have seen mutilated corpses; 13% have abducted someone; 28% have been wounded.
n A minor is abducted every three days in Colombia.
n A Colombian is murdered every 20 minutes.
n One in 25 Colombians is displaced.
n Each massacredisplaces 1,000 people. Around 1.5 million Colombians have fled homes after violence.
Council for Human Rights and Displacement; Bogota human-rights ombudsman; Human Rights Watch; UnicefReuse content