Once deemed the right-hand man of North Korean leader Kim Jong Un, Mr Choe Ryong Hae disappeared for three months after falling out of favour, supposedly over a power plant collapse.
Early this year, he resurfaced lauding Pyongyang's nuclear test.
Now he looks set for bigger things after his election to the Politburo Standing Committee (PSC), or top decision-making body, of the ruling Korean Workers' Party, which held its first congress in 36 years recently.
Analysts say Mr Choe is the man to watch, with some noting he could be tasked with mending ties with China and others thinking he could be put in charge of developing the economy.
More than half of the party's 235 central committee members were replaced during the four-day congress aimed at consolidating Mr Kim's power and cementing a shift from a "military first" doctrine under his father Kim Jong Il to a "party first" policy that prevailed under his grandfather Kim Il Sung, the nation's founder.
Mr Kim, 33, was promoted to party chairman, a position formerly held by his grandfather but not his father, in a move seen as his latest attempt to emulate the founder to build a credible image for himself.
Analysts had widely expected Mr Kim to replace the old guard with a new generation of young talents, but he kept most of them, including Mr Kim Yong Nam, 88, president of the Presidium of the Supreme People's Assembly who had served under all three Kim regime leaders.
This is the young leader's way of "showing respect to the old members who make up the foundation of his leadership", said international relations professor Park Ihn Hwi of Ewha Womans University .
Young additions to the central committee included Mr Kim's younger sister Yo Jong, 28. Analysts expect the vice-director of the party's propaganda and agitation department to continue to play a key role in supporting her brother - in the same way her aunt was part of her father's trusted inner circle.
Another emerging young talent is Mr Jo Yong Won, a deputy director in the party. "His special mission is not clear yet, but Kim Jong Un relies on him," said Prof Park.
However, these young leaders would have to wait in the wings while an older group of officials takes on key roles to shape the country's economy and foreign relations.
Premier Pak Pong Ju, a new PSC member, is expected to take charge of the country's economic development, while national intelligence chief Kim Yong Chol would preside over inter-Korea affairs.
Mr Choe could be a key player in North Korea-China relations since he had visited China earlier as Mr Kim's envoy, said Prof Park.
Relations between the two allies have been frosty since Beijing lost patience with Pyongyang for refusing to denuclearise, but Prof Park said a message sent by Chinese President Xi Jinping to Mr Kim to congratulate him on his appointment as chairman is a signal that ties might improve in the future.
Formerly the party secretary, Mr Choe played a leading role in preparing Mr Kim for succession back in 2009 and was widely considered as his right-hand man. But he was removed from his post supposedly due to a power struggle and sent for re-education to take responsibility for the collapse of a power plant.
Dr Choi Kang, vice-president of The Asan Institute for Policy Studies, described Mr Choe as capable and well trusted by Mr Kim, and said he could be entrusted with economic development plans this time.
"His comeback means Kim Jong Un is going to create his own group of supporters," he added.
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