In 2002, when Omar Khadr was a teenager, he followed his father on to the battlefields of Afghanistan, inspired by jihadist literature calling on Muslims to fight a holy war against Western invaders.
Eight years after his capture by American forces and his rehabilitation at Guantanamo Bay, the 23-year-old's wide reading tastes now include JK Rowling's stories about a British schoolboy who finds himself caught up in his own battle against the powers of evil.
Mr Khadr's transformation from child soldier to bibliophile shows how much he has grown up since his childhood days playing with the family of Osama bin Laden in Afghanistan. Today he is charged with war crimes against America at a trial before a military commission in a courtroom in Guantanamo Bay. He is accused of killing an American soldier with a hand grenade, and the US government appears determined to convict him.
His lawyers, who have spent many hours in his company, describe him as a "very gracious" young man who wants to show the world how much he has changed. Given his family background, however, that won't be easy.
The Khadr children had a strict Islamic upbringing in Pakistan before moving to Canada in 1992. Four years later, Omar's father moved them to Jalalabad, Afghanistan, where they often visited Osama bin Laden's compound. In 2003, his father – an alleged al-Qa'ida financier – was killed by Pakistani forces in a shoot-out near the Afghanistan border. Omar's younger brother Abdulkareem was left a paraplegic in the same battle. His older brother Abdullah, now 29, returned to Canada in 2005. He was arrested and faces extradition to the US on terrorism charges.
The white uniform that Mr Khadr wore to court on Monday shows that the Americans believe the man they accuse of war crimes is a model prisoner: detainees who refuse to co-operate must wear different coloured clothing.
Mr Khadr enjoys lenient treatment at the communal facility of Camp 4 on the south-east side of the island where detainees can mix outdoors with one another for up to 20 hours a day, and have access to an exercise yard for two hours a day. There is also a television room where films, nature programmes and highlights of international football games are shown. This is a world away from his earlier detention. He was first held in an interrogation centre in Bagram in Afghanistan. He claims he was abused and threatened with rape and death, and alleges that US soldiers once used him as a human mop to clean the floor because he had urinated on himself.
Today he spends his time in the camp library and running around the compound, but blames inadequate training shoes for a debilitating ankle injury. He also complains of back pains and is still worried about his left eye which was almost completely blinded in the battle in which he was captured.
A member of the Canadian foreign affairs office who visited Mr Khadr at Guantanamo in 2008 reported in a subsequently leaked document that the detainee chose to sleep on the floor rather than in his bed because of his back pains and the stomach aches which he claims are caused by the American shrapnel still inside his body. "He joked that it was the shrapnel which constantly set off the metal detector when being frisked going in and out of Camp Iguana [the facility where detainees meet visitors and lawyers]," the Canadian report said.
Despite his rehabilitation, however, Guantanamo remains a frustrating place to live. This was demonstrated recently when the camp guards refused to give Mr Khadr a pillow because of security fears.
The Canadian report concluded that this incident was difficult to justify, especially as Mr Khadr is "salvageable", "non-radicalised" and a "good kid". According to the Canadians, Mr Khadr believes he is a victim of his upbringing and seeks to redirect his life. "He said that he is in Guantanamo because of his family and that he wants another chance," the author wrote. He wants to train for a job that will allow him to play a useful role in society by helping others."
But on Monday, the court was shown another side of Omar Khadr that betrayed his residual hostility towards the West. In a video screened at his tribunal, Mr Khadr is seen telling Guantanamo Bay guards trying to weigh him for the International Red Cross "God will take... revenge" on the US. "I am here in prison, but there are millions of people outside," he says in the clip from May 2006. "What's happening to you is not for nothing."
In an affidavit from February 2008, Mr Khadr alleged guards mistreated him during the weighing session, claiming they "pressed on my pressure points". But the clip appears to show guards acting with restraint as they push him toward the scale and point out all other detainees were weighed without protest. "Come on man, it's not that bad," said one after Mr Khadr claimed the treatment was a "very small example of what's really going on" at the facility. "We're not doing this to hurt you, torture you," adds another, while explaining his weight was needed for his health records.
Although Mr Khadr spent 20 minutes resisting the guards, the tape hinted he had been playing to the camera as he switched from the English to Arabic in order to speak to fellow detainees in nearby cells. His Canadian lawyer, Dennis Edney, argued that his protests were the "peevish" behaviour of a young man whose manly appearance belied his juvenile mental state.
* The first prisoners arriving at Guantanamo Bay in January 2002 were shackled and made to wear orange jumpsuits. The specially built Camp X-Ray detention centre was so rudimentary that prisoners were forced to live in outdoor cages. Detainees were mostly kept in solitary confinement with very limited opportunities for exercise. Interrogation teams were also authorised to carry out torture techniques, including waterboarding.
* Conditions at Guantanamo began to ease before Barack Obama's election. Camp X-Ray was closed down after only a few months in 2002 so detainees could be separated into groups based on their security risks. The most compliant detainees are housed in Camp 4 where they enjoy communal living, regular exercise, a variety of meals and the chance to watch films and play sports. Less co-operative suspects are still held in isolation. But almost all of them have been in Guantanamo for more than eight years without charge.