Kim Jong Eun is portrayed in North Korea’s official media as a leader without comparison, blessed with a supreme bloodline, flanked by a supportive wife and endowed with the “brilliant” ability to revamp the economy, command an army and guide the space program.

But one thing is notably absent from these descriptions: any mention of his two brothers, both once rumored to be heirs to the family-run empire.

As Kim prepares for his nationally celebrated birthday on Tuesday, thought to be his 30th, his brothers are far from the state-sanctioned spotlight, one living in secrecy in North Korea, the other apparently moving between China and Singapore.

Their absence, North Korea watchers say, is integral to the personality cult that emphasizes Kim Jong Eun’s unique suitability to run the nuclear-armed nation. In state propaganda, he is depicted as an only son, his inheritance predetermined and uncontested.

North Korea has had just three leaders in six decades — Kim Jong Eun, his father and his grandfather — but the hereditary handoffs, in reality, have always caused bitter ­behind-the-scenes competition.

Kim Jong Eun was chosen by his father, Kim Jong Il, over his older male siblings, Kim Jong Nam, now 41, and Kim Jong Chul, 31. Kim Jong Il also had four daughters.

As the young leader tries to consolidate power, he has no apparent plans for his brothers, who represent potential rivals whom “other elites could coalesce around,” said Ken Gause, an expert on North Korean leadership at CNA, an Alexandria-based organization.

But Kim is believed to be grooming his youngest sister, thought to be in her mid-20s, as an aide. That mirrors the strategy used by his father, who gave his younger sister Kim Kyong Hui considerable power but banished his half brother into diplomatic exile. Kim Kyong Hui remains a major figure in North Korea, part of an inner leadership circle that includes her husband.

Secretive lives

Even before Kim Jong Il died about 13 months ago, Kim Jong Eun’s brothers led secretive lives — particularly Jong Chul, who has been photographed only a few times and has never spoken publicly. But after Kim Jong Eun ascended to power, his brothers withdrew almost entirely from public view, though experts emphasize that it’s unclear whether they were acting under orders.

Jong Chul, who is thought to live in North Korea, was last seen in public at a 2011 Eric Clapton concert in Singapore.

As for Jong Nam, he once led a lavish but secluded lifestyle in Macau, Asia’s gambling capital, where he wore European designer brands and gave occasional doorstep interviews to Japanese and South Korean media. But he hasn’t spoken to the media since last January, when he criticized North Korea’s hereditary power transfer and predicted trouble for his half brother. Yoji Gomi, a Japanese journalist, said Jong Nam also cut off contact with him after exchanging e-mails for several years.

In October, a man claiming to be a North Korean agent said he had been ordered to kill or injure Jong Nam by staging a car accident in China. The allegation came after the man was arrested in South Korea for unrelated activities — he said he had been sent there to monitor defector groups. The man, whose name was not given in court documents, said his orders to harm Jong Nam came from North Korea’s state security agency in 2010, the year Kim Jong Eun was officially anointed successor.

The agent said the plan unraveled because he couldn’t track down Jong Nam in China, according to court documents.

‘Zero power, zero influence’

Little is known about the true relationships between Kim Jong Eun and his brothers. Kim Jong Il’s seven children — born to his official wife and a series of mistresses — were raised in separate households across the country. A former Kim family sushi chef, Kenji Fujimoto, said last month in Tokyo that Jong Nam and Jong Eun have never met.

Jong Nam — Kim Jong Il’s child from an illicit relationship with an actress — was raised in near-isolation, according to the memoir of an aunt who helped raise the boy and later defected. Jong Nam had a massive playroom of toys, restocked annually by a team of globe-trotting purchasers. But Jong Nam felt he was living in a “luxury prison,” according to the memoir. When, as a teenager, he had an unsanctioned relationship of his own, his father threatened to send him to the coal mines.

Still, analysts presumed that Jong Nam, as the oldest son, was the heir apparent. But his chances probably evaporated in 2001 when he tried to enter Japan — with the hopes of visiting Disneyland — with a fake Dominican Republic passport. Jong Nam has since lived overseas.

Fujimoto, who briefly returned to Pyongyang last summer and met with Kim Jong Eun, said, “At present, in North Korea, Mr. Kim Jong Nam possesses zero power, zero influence.”

Experts say Jong Chul and Jong Eun, born to the same mother, might be closer. They attended the same international school in Bern, Switzerland, with several years of overlap, and later the same military university in Pyongyang.

Their mother, Ko Young Hui, was neither Kim Jong Il’s first love nor his official wife — he met her when she was performing in a state dance troupe — but many researchers say she was his favorite. Almost 10 years ago, state media began referring to her as the nation’s “respected mother.” North Korea watchers say the designation was significant: They thought her older boy, Jong Chul, was being groomed as successor.

Experts think that Kim Jong Il remained married to his official wife — Kim Young Sook — throughout his relationship with Ko Young Hui. Young Sook had only one child, a daughter.

How Kim Jong Eun outmaneuvered his brother to gain control of the country is unclear, with speculation based on the frailest of character sketches because North Korea has managed to keep a near-perfect seal on biographical information about Jong Chul.

Fujimoto, in a 2003 tell-all book about life with the Kims, described the young Jong Chul as effeminate and uninterested in politics. Chinese experts and visitors to North Korea also have been quoted — in State Department cables released by the anti-secrecy group WikiLeaks and in the Japanese media — as describing Jong Chul as a video game devotee who was often sick.

Around 2005, experts began to say that Jong Eun was favored by his father.

Some experts say that Jong Chul could have an unlisted position in the Workers’ Party, based on rumors from high-level defectors, and that he could one day emerge publicly.

“But right now,” said Cheong Seong-chang, an expert on North Korean leadership at the Sejong Institute on the outskirts of Seoul, “he is supporting his brother by staying silent and keeping out of the public eye.”

Yoonjung Seo in Seoul and Yuki Oda in Tokyo contributed to this report.