Dear leader prepares to hand over – to his nearest and dearest

As the North Korean ruler's era nears its end, speculation is growing about who will control the reclusive state

It is one measure of the secrecy surrounding North Korea's leadership that we barely know what the country's putative new leader looks like, what he thinks or even exactly when he was born. So, speculating on his abilities for the job of helming the crumbling Stalinist backwater is hardly relevant except in the only sense that it matters: as the youngest son of Kim Jong-il, current ruler in the world's sole hereditary dictatorship, he has the one qualification that really counts.

Kim Jong-un is 27 or 28, reportedly likes Belgian martial artist Jean-Claude van Damme, can hold his Soju – a Korean spirit - and speaks English, German and French. As a child he drove a specially adapted Mercedes Benz around his father's estate and liked to play basketball, according to Kenji Fujimoto, Kim Senior's former sushi chef – a key source for the little we know about the Kim dynasty. Mr Fujimoto is responsible for one of the few verified images of Jong-un – a snap he took in the 1990s while living with the family.

If, as reported, the 11-year-old boy with the pudding-bowl haircut in this photo eventually takes over from his ailing father, his biographers will inevitably have to peer through the thick fog of disinformation and ornate propaganda that surrounds Pyongyang's first family. Korea-watchers are already intrigued by the role of his mysterious uncle, Jang Song-taek, 64, a once anonymous cadre who has leapfrogged over a long line of contenders to become the nation's de facto No.2.

There seems little doubt that the North's ailing leader, Kim Jong-il, 68, is preparing to transfer power, perhaps even as early as next month, when the leadership holds a rare party conference – the first in 30 years. Some observers predict the conference may in effect be Kim junior's political coronation – Jong-un was given authority over the Workers' Party and the military last year, said Cheong Seong-chang, a senior fellow with the Sejong Institute, a Seoul-based think tank. "From the summer of 2009, all official reports made to Kim Jong-il went through Jong-un," he told The Korean Herald this month.

Official propaganda has become suitably florid, welcoming Jong-un as "the number-one guard of [Kim Jong-il], stepping first to the General's on-site guidance visits to every site without regard to any conditions; in all weather, any temperature or wind and any landscape", according to the online newspaper, Daily NK.

Kim Senior is quoted as calling his son "a genius of geniuses" in propaganda distributed to party cadres. "There is nobody on the planet who can defeat him in terms of faith, will and courage."

If the prospect of putting an untested young kickboxing fan in charge of a prickly, nuclear-armed state sounds terrifying, it clearly worries the North's ageing ruling elite, too. Kim Senior has reportedly surrounded his son with more experienced elders who are shepherding him through the transition. And his leading mentor is Jang Song-taek, who has survived a purge, marriage to the Dear Leader's sister, Kyong-hee, 63, and the tragic death of his daughter – she reportedly killed herself in France after her parents demanded she end a relationship and return home.

In June, Mr Jang was appointed chairman of the National Defence Commission – the North's supreme governing body, making him the country's effective second-in-command, behind the Dear Leader. The appointment was a surprise to some, since Mr Jang was widely thought to have been purged by his brother-in-law from 2004-6 – punishment for flaunting his opulent cadre's lifestyle.

But as Mr Kim's health ebbs following a stroke two years ago, he appears to be leaning on family members he can trust – his sister, son and brother-in-law.

As with most of the North's elite, information on Mr Jang is sketchy. He was for years head of the country's internal security, an enforcer who locked up state enemies.

There is little doubt he is close to Mr Kim, having been photographed dozens of times at his side. He is thought to be close to the younger Mr Kim. "The good news about Jang Song-taek is that he knows something about the world of business, trade and finance. The bad news is that he has a long history of corruption," says Bradley Martin, author of Under the Loving Care of the Fatherly Leader.

"Some outside analysts have seen Jang as a prospective economic reformer, but based on his record the changes he might want to put into effect would be those benefiting not the ordinary people but himself and some fellow high-ranking officials."

His young charge is also a largely unknown quantity. South Korean sources say Jong-un's mother was Koh Young-hee, a dancer and one-time consort to Kim Senior.

After her death, apparently from breast cancer in 2004, the North Korean military began referring to her as "Respected Mother", fuelling speculation she was being elevated in the pantheon of state heroes to further her son's political career.

According to Mr Fujimoto, Jong-un is a sporty and strong-willed boy who "knew how to lead people", unlike his "feminine" older brother, Jong-chul, who mortified his father when he tried to visit Tokyo Disneyland on a forged passport in 2001.

Thereafter, the information trail begins to dry up. His January birthday reportedly became a national holiday this year, according to Free North Korea Radio, which monitors life across the demilitarised zone. "We believe he has a good chance of taking over from his father, but many inside and outside the North are asking questions about his skills as a leader," said the station's head, Kim Seong-min.

The lack of hard evidence means that official state events are carefully watched for their wider significance. In May, Kim Jong-il was seen inspecting a shoe factory with his youngest son, who he reportedly calls "Captain". According to the pro-democracy broadcaster, Open Radio for North Korea, millions of portraits of Jong-un are ready to be hung beside his father and his dead grandfather, Kim Il-sung.

If this speculation proves correct, Jong-un will take over a deeply troubled country, in the words of Pyongyang expert Gavan McCormack: "Beyond the 'pale' of civilisation, closed, threatening, idolatrous; yet, at the same time... on the surface at least, an urban, educated society."

Nuclear-armed, with the fourth biggest standing army in the world, obsessed with old enemies: the North has still to absorb global changes that have taken place since the 1980s.

Growing access to DVDs, radio and other sources allows the North's citizens to compare their impoverished lives with prosperity elsewhere. Discontent is widespread following a botched currency reform and years of stagnation, a process that accelerated following the 1991 collapse of the Soviet Union, and a mid-1990s famine that killed an estimated two million to three million people.

Caught in this catastrophe, Jong-un's father has wavered between attempting to engage with the outside world and retreating to sharpen the spines of what Mr McCormack calls the porcupine state. In 1993/4, Mr Kim took the country to the brink of confrontation with the Clinton administration by producing plutonium for a long-planned nuclear weapon, before agreeing to a freeze in return for the construction of light-water nuclear reactors. The so-called "Agreed Framework" collapsed under US president George Bush, with allegations of bad faith on both sides.

The exchange chilled relations, even before the election of a conservative South Korean president and the sinking of a South Korean frigate this year, which has brought back talk of war. How will a young man with little known qualifications except the right genes and a spell in a posh Swiss school fix this mess? Will his uncle's political skills help him to survive? And will the great mass of North Koreans passively accept another dynastic handover of power?

These questions will make the rise of Kim Jong-un and Jang Song-taek a compelling political drama.