As North Korean leader Kim Jong Un has sought to raise his international standing, a figure seen by his side almost constantly during his meetings with world leaders is none other than his younger sister Kim Yo Jong.
Those frequent appearances have taken on a new significance in recent days, as rumors swirl that the dictator is gravely ill after a surgery. Kim Jong Un's line of succession is hazy — he is believed to have three children, but they are too young to take control over the country, and his brother has reportedly been deemed unfit to lead.
That has prompted speculation that Kim Yo Jong is next in line, though the country has never had a female leader.
During the two summits between the US and North Korea, Kim Yo Jong was front and center during the historic show of diplomacy between Kim Jong Un and President Donald Trump.
She also traveled to South Korea during the 2018 Winter Olympics, becoming the first member of North Korea's ruling family to visit the south since the Korean War in the 1950s.
Like her brother, and much of the rest of their family, few details are known about Kim Yo Jong and the life she lived before reaching a prime leadership role in the North Korean government.
Here's what we know about her so far.
Like many of Kim's family members, Kim Yo Jong's exact age is difficult to pin down. But she's believed to be in her early 30s, likely born in 1989.
She's the youngest child of former North Korean leader Kim Jong Il and his consort, Ko Yong Hui, a former dancer.
She was partly educated in Switzerland at the same school Kim Jong Un attended. But she returned to North Korea in 2000 after completing the US equivalent of the sixth grade.[rebelmouse-proxy-image https://media.rbl.ms/image?u=%2F5c76d86b2628981e0e185319%3Fwidth%3D1300%26format%3Djpeg%26auto%3Dwebp&ho=https%3A%2F%2Fi.insider.com&s=327&h=f892c8a2729aafffe7a2825c410497bf48761ebcad11d2871036e6f55e3653b1&size=980x&c=3282151137 crop_info="%7B%22image%22%3A%20%22https%3A//media.rbl.ms/image%3Fu%3D%252F5c76d86b2628981e0e185319%253Fwidth%253D1300%2526format%253Djpeg%2526auto%253Dwebp%26ho%3Dhttps%253A%252F%252Fi.insider.com%26s%3D327%26h%3Df892c8a2729aafffe7a2825c410497bf48761ebcad11d2871036e6f55e3653b1%26size%3D980x%26c%3D3282151137%22%7D" expand=1]
The Liebefeld-Steinhölzli public school in Köniz, Switzerland.
Kim Yo Jong appeared destined for a powerful career from a young age. Kim Jong Il once bragged to foreign interlocutors in 2002 that his youngest daughter was interested in politics and eager to work in North Korea's government.
It's completely unclear where she was or what she was up to between 2000 and 2007.
In the following years, she conducted a lot of behind-the-scenes work for her father, Kim Jong Il, and brother Kim Jong Un. She played a particularly significant role in helping Kim Jong Un take over instead of his older brothers.
Her first public appearance was in 2011 at Kim Jong Il's funeral.
Kim Yo Jong made headlines in 2017 after she was promoted to a top position in her brother's government: the head of the propaganda department of the Workers' Party of Korea.
That's not just a fancy title — Kim Yo Jong plays a crucial role in controlling her brother's public image.
In public, Kim Yo Jong appears to have greater freedom than other top government officials in North Korea, occasionally appearing in photographs unaccompanied, rather than constantly being in the presence of Kim Jong Un.
Some have speculated that she was promoted partly in an effort to continue Kim Jong Un's dynasty. While she's out of the line of succession, some believe she could take over the country's leadership if something happens to Kim Jong Un before his kids are old enough to rule.
It wouldn't be an unprecedented role for her, either. Kim Yo Jong once briefly took control of the country's affairs while her brother was ill in 2014, according to a South Korean think tank run by North Korean defectors.
She stepped onto the world stage in February 2018. In a rare show of diplomacy between the two Koreas, Kim Yo Jong traveled to South Korea for the Winter Olympics in Pyeongchang.
Everyone's eyes were on Kim Yo Jong at the start of the games. She shared a historic handshake with South Korean President Moon Jae In, and both broke out in smiles.
During the opening ceremony, she sat right behind US Vice President Mike Pence, second lady Karen Pence, and Japanese Prime Minister Shinzo Abe.
Kim Yo Jong and Pence did not speak with each other.
Her interaction with South Korean leaders was a rare show of diplomacy and warmth. Given her experience in propaganda, she likely knew exactly what she was doing to try and curry favorable attention.
In April 2018, she played a crucial role in the peace talks between the two Koreas. Leaders from the two nations met at the Demilitarized Zone, and Kim Yo Jong was notably the only woman at the table.
Though she stayed well away from the spotlight, leaving that to her brother, it was clear Kim Yo Jong played a significant role in orchestrating the talks and ensuring the day ran smoothly.
She was her brother's right-hand woman when he and Trump signed the agreement acknowledging North Korea's intentions to denuclearize.
Kim Yo Jong sparked curiosity at one point, when she switched out the pen that was provided for the summit with her own ballpoint pen. It's unclear why she swapped the pens, but some have speculated that it was for security reasons.
She made headlines in February 2019 when she was seen holding her brother's ashtray while he smoked during their train journey to Hanoi, Vietnam.
Kim Yo Jong was featured prominently in the preparations for her brother's talks with Trump, often rushing ahead to make sure everything was ready.
She even went viral at one point when she seemed to be hiding in the plants as Kim Jong Un met with the US president at the Metropole Hotel.
It has become increasingly clear over the past several years that Kim Yo Jong was one of her brother's most trusted officials, and her power in the regime was only growing.
But in the Hermit Kingdom, no one's position is ever truly secure under the mercurial leadership of Kim Jong Un. He's known for turning on family members quickly when they fall out of favor — and it remains to be seen whether Kim Yo Jong is an exception.
Kim Yo Jong was not listed as an alternate member of North Korea's ruling Workers' Party of Korea politburo — the party's top decision-making body — and did not appear at any high-profile events during an important party gathering in April 2019.
She also missed a meeting between Kim and Russian President Vladimir Putin later that month, fueling speculation that she had been demoted.
One theory is that Kim Jong Un ordered her to lie low after his failed summit with Trump in February 2019.
But in early June 2019, Kim Yo Jong was spotted for the first time in 52 days, suggesting she was back in her brother's good graces.
In October 2019, North Korean media released strange photos of Kim Jong Un riding a white horse atop a mountain with historic and symbolic significance.
Experts told Business Insider that the photos are packed with political meaning — and could foreshadow a frightening military advancement.
Since then, her profile has only grown. In March 2020, Kim Yo Jong made her first-ever public statement, insulting South Korea as a "frightened dog barking" after the country condemned one of North Korea's live-fire military drills.
"Such incoherent assertion and actions… only magnify our distrust, hatred and scorn for the South side as a whole," Kim Yo Jong said in the statement.
The following month, Kim Yo Jong was reinstated as an alternate member of the Workers' Party of Korea politburo, suggesting that all has been forgiven since the collapse of last year's summit.
Given these recent developments, it's clear that Kim Yo Jong's power has grown tremendously in recent years, fueling speculation that no other family members besides her could take over.