Not too long ago, even the most devoted watchers of North Korean politics knew little to nothing about Kim Yo-jong.
The sister of dictator Kim Jong-un and youngest child of the hermit nation's late Supreme Leader, Kim Jong-il, had spent her life in the shadows until she appeared at her father's funeral in 2011.
Less than a decade later, her triumph on the world stage at the Winter Olympics in South Korea demonstrated her meteoric rise through the often-brutal ranks of Pyongyang's leadership.
Recent major developments indicate she's grown that power and is the likely heir to the North Korean leadership – whether her brother likes it or not.
A ruthless ambition emerges
In mid-2020, while the world was gripped by the worsening Covid-19 pandemic, Kim Yo-jong blew up a building.
The Korean Liaison Office on the Northern side of the demilitarisation zone – a neutral strip between the two countries – was flattened by the military at her behest.
"I feel it is high time to surely break with the South Korean authorities," she declared just days earlier, saying she had ordered the building to be "completely collapsed".
The building was empty of people, but Kim's snap destruction of such a symbolically important site took the South by surprise, given the optimism harnessed less than two years earlier.
In 2018, she led a delegation to the Winter Olympics in PyeongChang, becoming the first figure of her family's political dynasty to visit the South in a formal capacity.
Kim met with South Korean President Moon Jae-in and posed for photographs with Japanese Prime Minister Shinzo Abe and American Vice President Mike Pence.
At home, vision of her successful visit dominated state-controlled media and pundits declared it a sign of her leadership ambition.
Sojin Lim is a senior lecturer in Korean Studies and deputy director of the International Institute of Korean Studies at the University of Central Lancashire and said the "first sister" has enjoyed a continued rise.
A fresh sign of this emerged last week, after Moon spoke at the United Nations General Assembly and called for an end to the war on the Korean peninsula. It's a plea for peace that he has made numerous times, and as usual, it sparked a bitter rebuff from North Korean officials.
But in stark contrast, just a day later, Kim Yo-jong said the idea of peace is "admirable" – albeit on a number of conditions.
"What needs to be dropped is the double-dealing attitudes, illogical prejudice, bad habits and hostile stand of justifying their own acts while faulting our just exercise of the right to self-defence," Kim said.
That kind of rhetoric, especially one of such significance, would normally come from her brother, Lim wrote in an article for The Conversation.
"Another interesting episode can cast some light over power relations between herself and her brother," she said.
"In March 2020, Kim Yo-jong issued her first official statement, lashing out at South Korea's presidential office, the so-called Blue House, which had called on the North to halt its live fire exercises. She referred to the leadership as 'a mere child' and 'a burnt child dreading fire'.
"Two days later Kim Jong-un sent a message of condolence over the outbreak of Covid-19 in the South. This 'underlined his unwavering friendship and trust toward President Moon and said that he will continue to quietly send his best wishes for President Moon to overcome'.
"The message had Korea watchers confused as to whether the siblings were at loggerheads over North-South relations or whether this was a display of 'good cop-bad cop' diplomacy."
A fierce battle for power
Speculation about Kim Jong-un's health intensified once more recently when the leader made a public appearance sporting a significantly slimmer frame.
Years of illness rumours have constantly followed the sighting of strange bruises on his body, as well as poorly concealed bandages.
Leonid Petroc, a Korean Studies expert at the Australian National University, said should something happen to Kim, a "fierce power struggle is inevitable".
"A collective leadership composed of the military top brass and party elders is likely to step in and run the country," Petroc told news.com.au.
"Kim Yo-jong might be too cruel and unpredictable for the North Korean elites to tolerate. They have been living in fear long enough and will not need another despot with new rules of survival."
The party and the army could turn to a "softer – and weaker" family member to lead, to give them legitimacy to rule North Korea, he said.
But the country is running out of potential candidates, as many possible male heirs have been executed or assassinated.
"Including Kim Jong-nam, Kim Jong-un's half brother who was murdered with the nerve agent VX at Kuala Lumpur airport in Malaysia in 2017," Dr Lim said.
"And his uncle, Jang Song-thaek, who was reportedly executed by firing squad in 2013 after being accused of being a counter-revolutionary.
An heir apparent?
Lim said securing the leadership of North Korea seemed to hinge on seizing control of the "trinity power of the military, party and people".
Kim Yo-jong has solidified herself as a foreign relations powerhouse.
"Following what was reported as her diplomatic triumph at the Winter Olympics, her profile grew as she met with the Chinese President, Xi Jinping, and was present at all three face-to-face meetings between her brother and US President Donald Trump," Lim pointed out.
"She has twice been elevated to the politburo, in 2017 to 2019 and 2020 to 2021.
"In addition, she is also a leader of the Propaganda and Agitation Department, in which capacity she has boosted the cult of personality surrounding her brother as well as making regular statements about North Korean foreign relations.
"She is believed to be married to Choe Song, the younger son of the Korean Workers' Party secretary, Choe Ryong Hae, which gives her another source of political power."
Those factors give her strong recognition among the people of North Korea, as well as influence within the party.
"But she has not yet been appointed to a position at the National Defence Commission," Lim said, pointing out that her father and her brother both became leading figures in the NDC, which controls the military.
"If that happens any time soon, it might be a sign that North Korea is preparing for its first woman leader."
And that would make her one of the most powerful woman in the world, and one of the most dangerous, at the helm of an unstable regime with dozens of nuclear warheads.