It would reach 40C in the Saudi Arabian city of Jeddah during the summers of the early 1970s, when Dr Khaled Batarfi was a teenager. Each year, new skyscrapers were built in the sand, transforming the once-barren desert into a swarming metropolis.
When he was about 14, a new family moved in next door on their wealthy residential street. He introduced himself to their son – a curly-haired teenager named Osama bin Laden, whom he recognised as one of the many children of the ultra-wealthy Mohammed bin Laden, a local construction magnate who was killed in a plane crash a few years earlier.
The pair struck up a close friendship, forming a football team with some other boys on their street. The first in the group to get a car, bin Laden used to drive them all to the Red Sea on Thursdays for sunset matches and picnics on the beach.
If anything, Batarfi remembers his former best friend as a shy, sensitive teenager – attributes all the more difficult to square with his transformation into the world's most wanted man.
As founder of Islamist terror group al-Qaeda in 1988, bin Laden was responsible for thousands of deaths across the world; some 2996 in the September 11 attacks in New York in 2001.
Batarfi can still scarcely believe it. "We played football together, we sang. He wasn't a talker; he would listen more than he spoke. How is it possible that this boy turned into this monster?" the 61-year-old asks himself today, over Zoom from his study in Jeddah. The author and journalist speaks with impeccable English, thanks to his time working as a Saudi correspondent for a British publication in the 1980s.
In the run-up to the 20th anniversary of 9/11, most have chosen to focus, understandably, on the victims. But for Batarfi, this time of year always causes him to reflect on the tragedy's architect, who masterminded the attacks from a fortified network of caves in Afghanistan.
As teenagers, the pair walked to the mosque each weekend for prayers, chatting about football and films; bin Laden was a particular fan of Westerns (favouring the cowboys over the Native Americans because "they had all the guns", Batarfi remembers).
During one football match, he suffered a nasty tackle from the opposing team. Batarfi ran over to protect his friend, shoving the other boy away. Bin Laden later told him: "If you'd given me just a few minutes, I would have resolved this peacefully."
The teenage bin Laden was vehemently opposed to Israel, as were most of his peers. But "he never showed hate or the kind of anger we saw later", says Batarfi. "It was more support for the Palestinians against Israelis; he didn't have hate against the West."
On religion, he was markedly more pious. One day, on the way to football, Batarfi remembers bin Laden criticising him for wearing shorts, which he considered a contravention of Islamic custom. At other times, he would quiz his friends on Islam, awarding cakes for correct answers.
According to the popular narrative, bin Laden's deadly ambitions were spurred on by the death of his famous father, but Batarfi doesn't buy it. "[Bin Laden] had over 40 brothers and sisters around that time, and he was one of the late ones. His father was a very busy man. I'm not seeing a son who was close to his father."
Far more significant was bin Laden's mother, Alia Ghanem (Mohammed's 10th wife), a Syrian beloved by Batarfi and their friends. "She was like a mother to all of us. So sweet, kind, trusting. She loved us like her children."
She was devastated in 1979, he says, when her 21-year-old son travelled to Afghanistan to join the fight against the Soviet invasion. Bin Laden initially promised his mother he was only going to offer humanitarian assistance, but within four years he was hiding in the Sulaiman mountains, on the front line. "She was so afraid."
Batarfi and bin Laden still met up once or twice a year during the 1980s, when he returned from Afghanistan to visit his mother. Batarfi was on the first rungs of his career as a journalist, and bin Laden at one point asked whether he might like to join the jihad. "He said: 'You have a sword and your sword is your pen. Come and see for yourself; write what your conscience tells you'." Batarfi, whose wife was pregnant at the time, refused.
The pair met for the last time in 1990, at the end of the Afghan-Soviet war. Batarfi thinks that period marked a crucial turning point in his friend's descent into evil. Before then, he could reasonably have been described as a freedom fighter, defending his fellow Muslims from Russian attack. But from the late 1980s his ideology morphed into a maniacal hatred of Western civilisation itself.
Why did his friend take such a destructive path? "When people go to a bloody war, they don't come back the same. They enter the terrible mood of war – kill or be killed. When he came back to Saudi Arabia, [he was] feeling out of the game. He was not ready to retire yet... he became an addict of war."
Batarfi was studying at the University of Oregon in 1998, when al-Qaeda bombed US embassies in Kenya and Tanzania, claiming more than 200 lives. From his student apartment, he watched on television as President Clinton condemned bin Laden by name. "It was a shock when I heard his name – the most powerful man in the world talking about this shy friend of mine."
Bin Laden's rambling video addresses to the West became popular currency on American TV – but Batarfi could barely stand to watch them. "The face, the voice – it's him," he says, "it's just the content that's different. It's like a recorder from which you used to hear music, and suddenly you hear sirens."
In September 2001, Batarfi was in his newspaper office in Jeddah when he noticed colleagues running towards a TV. He looked over and saw images of planes hitting the World Trade Centre. "I said [to my colleagues], 'If this was caused by any Muslim or Arab, we're in big s---'." A week later, he watched on television as George W Bush blamed his childhood friend by name. By that point, Batarfi says, he was largely immune to shock.
In an interview in 2018, one of bin Laden's half-brothers, Ahmad, said their mother remained "in denial about Osama... She loved him so much and refuses to blame him. Instead, she blames those around him. She only knows the good boy side, the side we all saw. She never got to know the jihadist side."
Batarfi remained close to the rest of the family and is in regular contact with two of bin Laden's children: Abdullah, the eldest son; and Omar, who married a Cheshire parish councillor in 2006.
But he remembers his immense relief on May 1, 2011, when President Obama announced his friend had been shot dead in his safe house in Abbottabad, Pakistan at the hands of US Navy Seals – reportedly cowering behind one of his wives.
"Even the people who loved him were relieved, that finally he exited this terrible game and terrible war against the world," he says. "It's like someone you care about has cancer, a disease that is hurting him, changing him, affecting his mentality and affecting everybody around him. You pray he will die to get out of his misery. And Osama created misery for everyone."