About 20 years ago, while travelling across Russia in his forest-green armored train, Kim Jong Il is reported to have made something of a confession to a foreign emissary.
It was 2001 and the North Korean leader was touring the country for three weeks. Accompanying him was Konstantin Pulikovsky, a respected Russian diplomat who, as the story goes, used the rare opportunity with one of the world's most reclusive leaders to talk about family.
Kim was believed to have had seven children. His youngest son and future successor, Kim Jong Un, was in his mid-teens at the time. It wasn't until several years later that the North Korean leader's health would start failing him, and it's not clear if he had begun thinking about his legacy and how to keep the family dynasty going.
So when Pulikovsky asked about the children, Kim spoke highly of his two daughters.
His sons, however, he called "idle blockheads."
Michael Madden, an expert on North Korea's leadership who runs a website on the subject and is a government consultant, said he's repeated that anecdote many times over the years when asked about the Kim family. The story has been repeated in various media and academic reports several times since 2001, but CNN could not independently confirm it.
"Kim Jong Il loved his sons, but did not necessarily have a high opinion of what they were doing with their lives," Madden said.
Despite that apparent assessment, Kim eventually chose his youngest son to succeed him. The grooming process began about eight years later, in 2009, when Kim Jong Un was given a coming out party. Kim Jong Il died of a heart attack two years later.
While it's likely the world will never know if Kim seriously considered one of his daughters for the top job, his adoration for his youngest child, Kim Yo Jong, has been well documented by North Korean standards. Kenji Fujimoto, the pen name of a former sushi chef for the Kim family, told The Washington Post that Kim Jong Il referred to her as "Princess Yo Jong" and "sweet Yo Jong."
Kim Yo Jong always sat to her father's left at supper, while Kim Jong Il's wife sat to his right, Fujimoto said in a book recounting his experience in North Korea.
However, Kim Jong Il may have believed that it would be a tough sell naming a woman as the next North Korean leader -- especially with multiple sons available.
North Korea is a notoriously patriarchal country, where women are expected to be dutiful and subordinate wives and doting mothers before all else. Defectors say misogyny, gender discrimination and sexual violence are rampant.
"There's a base culture of just very strong, traditional patriarchal gender norms and female disempowerment," said Sokeel Park, the director of research and strategy for Liberty in North Korea, a human rights group that assists defectors.
Yet Kim Yo Jong's position among the North Korean leadership is significant. Her name was among the first mentioned as a possible successor to her brother when he disappeared from public view for almost three weeks, only to emerge in state media Saturday with Kim Yo Jong by his side.
A photo released from North Korea's official Korean Central News Agency on May 2 reportedly shows North Korean leader Kim Jong Un at an event in South Pyongan province with his sister Kim Yo Yong, left. CNN cannot independently confirm the reporting of KCNA.
Kim Jong Un's mysterious absence prompted important questions about North Korea's plans for the future -- especially given that he is overweight and reportedly both a heavy smoker and drinker.
Experts say if anything was to happen to him before his young children are old enough to take over, Kim Yo Jong could be the safest and most likely heir. If she did succeed Kim, it would put a woman at the center of one of the most repressive regimes on the planet.
Gender divide
The Korean Peninsula isn't an easy place to be a woman.
North Korea is hardly the bastion of equality that Kim Il Sung promised would be achieved through economic liberation.
While women are an important part of the workforce, and drivers of the limited private markets inside the country -- since all men have jobs assigned by the state -- female defectors say they still face widespread discrimination. Furthermore, they lack the professional and social opportunities of their male counterparts.
"Women always have to be modest," said Nara Kang, who left North Korea in 2015 and now lives in the south. "Men hold the purse strings a lot of times and men have all the social status."
Sexual violence is also a major problem. It's "so common that it has come to be accepted as part of ordinary life," Human Rights Watch alleged in a 2018 report.
North Korea denies this, as it does all allegations of widespread abuses -- which it often refers to as an imperialist "human rights racket." "Women enjoy equal rights with men in all fields," diplomats from the country wrote to a United Nations panel on women's issues in 2017.
Kang says the situation is better in South Korea, but it's not ideal. The country ranks at the bottom of all OECD countries in terms of the gender wage gap. Women regularly face workplace discrimination and harassment in public, including illicit filming in toilets.
Jean Lee, an Associated Press reporter who opened the wire service's bureau in Pyongyang in 2012, said she's endured "incredible sexism in both countries."
"My female North Korean colleagues had the same complaints as my female South Korean colleagues: that they were expected to do their jobs all day and still take care of all the cooking and cleaning at home," said Lee, who is now the director of the Hyundai Motor-Korea Foundation Center for Korean History and Public Policy at the Woodrow Wilson Center in Washington, DC.
"To be honest, neither Korea, north or south, is a great place to be a woman."
But the south does have one calling card: it has had a female leader.
Park Geun-hye broke South Korea's highest glass ceiling in 2015, becoming the country's first elected woman president.
Madden, the North Korean leadership expert, believes that although Park's tenure ended in scandal, she proved that a woman can be accepted as a leader in Korea -- north or south.
"North Korea has a 70-plus year history of women being very close to the center of power, of being influential in North Korea's decision-making processes," he said. "South Korea already broke the mold on the Peninsula."
Kang, the defector, isn't so sure. When asked if while living in North Korea she imagined there could be a female Supreme Leader, Kang responded incredulously.
"Oh no way," she said. "I can't even imagine. Can't even dream."
An unbreakable bond
From the moment Kim Yo Jong set foot on South Korean soil in 2018, the cameras followed her everywhere. Her job was to represent her brother's regime at the Winter Olympics in the South Korean city of Pyeongchang, and she wasn't even the highest ranking member of the envoy -- that title belonged to Kim Yong Nam, who was at the time North Korea's ceremonial head of state.
But Kim Yo Jong was the one really making history. She became the first member of North Korea's ruling family to go south of the 38th parallel since 1953, when the Korean War effectively ended (the war is still technically ongoing because the fighting parties signed a truce, not a treaty.)
Experts knew Kim Yo Jong was one of the Supreme Leader's top aides and confidants. As the deputy director of the Propaganda and Agitation Department of the Workers' Party, she was responsible for crafting her brother's public image and messages.
But the year before the visit to South Korea, she had also joined the country's Politburo -- the senior body of North Korea's ruling party -- as an alternate member, adding another important title to her resume.
But average South Koreans knew little else about her, and the mystery bred curiosity. People were fascinated by this seemingly urbane emissary from what is often portrayed as a backwards country, representing a leader who, at the time, had not traveled abroad since taking power.
As governor of the South Korean province where the Olympics was hosted, Choi Moon-soon met with Kim Yo Jong. He described her as "very calm and self-possessed," a woman of "very few words" but who speaks precisely and directly.
During her trip, Kim Yo Jong cheered on the inter-Korean hockey squad and took in the opening ceremonies alongside South Korean President Moon Jae-in and US Vice President Mike Pence, who chose not to shake her hand. She was photographed watching events and performances, smiling and seeming to get along well with her hosts. The press even likened her to a North Korean Ivanka Trump.
It was masterstroke in public relations by one of North Korean's top propagandists.
She put a human face on a regime that, at the time, the Trump administration was trying to castigate as a pariah state and nuclear renegade. And she did it while also laying the groundwork for her brother's diplomatic push, which would see him become the first North Korean leader ever to meet face-to-face with a sitting US president.
The visit proved not just to be Kim Yo Jong's coming out party to the world; she showed just how good she was at a role she had spent much of her life preparing for.
Kim Yo Jong's exact birthday is unclear, but she's believed to be in her 30s. When she was sanctioned by the US Treasury Department for the regime's human rights abuses and extreme censorship activities, it was listed as September 26, 1989. But South Korean intelligence has said she was born in 1987. Further details on her childhood are scant.
What we do know is this: Like Kim Jong Un, Kim Yo Jong studied in the Swiss capital of Bern as a young child, her aunt and uncle who helped raised them told The Washington Post in an interview. Madden said on his blog that she spent about four years there, until she completed the equivalent of sixth grade in the US.
In Switzerland, the adults around Kim Yo Jong and Kim Jong Un attempted to give the children a normal life, but they all had to keep so many things secret -- their real identities, their wealth and their mother's ongoing treatment for terminal breast cancer at the time.
The Kim siblings shared a childhood that was remarkable but uniquely solitary and lonely. It was an experience that few can empathize with. Kim Jong Il would have been the one to decide to raise them together, and experts like Madden believe it may have been on purpose.
"As they've grown older and grow more aware of the circumstances in which they grew up, it's a pretty harsh reality to face. And of course that's a hard reality that they face together," Madden said.
"Nobody can relate to that. Kim Yo Jong and Kim Jong Un, I believe that they have a relationship that is impossible to break."
The Paektu bloodline
Given the intense secrecy surrounding the Kim family, we may never know how hard it was for Kim Yo Jong to surmount gender discrimination to rise to the top of North Korea's political hierarchy.
But Kim Yo Jong is no ordinary woman.
Kim Jong Il had more children than Jong Un and Yo Jong, and the siblings still have living aunts, uncles and cousins. But Madden says Yo Jong and Jong Un are the only two lionized in state media as the true heirs of Kim Il Sung's "Paektu bloodline," a reference to the mythical mountain on North Korea's border with China.
"There's no other legitimate descendant of Kim Il Sung as far as North Korea's political culture is concerned," Madden said.
If Kim Jong Il wanted her close to the levers of power, it's now clear the late North Korean leader got his wish.
All of the experts CNN spoke to for this story agreed with the theory that being a woman will not hold Kim Yo Jong back. But that has more to do with her status than changing gender dynamics within North Korea.
"Gender, I don't think is insurmountable," said Park of Liberty in North Korea. "It would obviously be a first and it is a patriarchal system and so on, but I think that Paektu bloodline, the Kim bloodline, overrules that."
Lee, the former AP bureau chief in Pyongayng, said she also believes that her heritage "is more important to the Kims than gender."
"For years, Korea watchers have been saying that North Korea would not accept a woman," she said. "I've been saying for years that it's quite possible the next leader of North Korea will be a woman -- as long as she's the best Kim for the role."