South Korean President Moon Jae-in, right, talks with Kim Yo Jong, North Korean leader Kim Jong Un’s sister, during a performance of North Korea’s Samjiyon Orchestra at the National Theater in Seoul on Sunday, Feb. 11, 2018. (Bee Jae-man/Yonhap/AP)
Lucy K. Pick is senior lecturer at the Divinity School in the University of Chicago. Her most recent book "Her Father’s Daughter: Gender, Power, and Religion in the Early Spanish Kingdoms," considers the role of royal women in the power structures of early medieval Spain.

PyeongChang is buzzing, but the biggest topic of conversation during the first few days of the Winter Olympics hasn’t been about a snowboarder or a figure skater. It has been about Kim Yo Jong, the 30-something sister of North Korean leader Kim Jong Un, who accompanied the North Korean delegation to the Olympics and attracted attention everywhere she went, from the Opening Ceremonies to Saturday night’s hockey game. She has remained in the news even after returning to North Korea.

The Western world’s preoccupation with the dictator’s sister has provoked plenty of blowback and is partly a result of hunger for any information about the secretive North Korean regime. But it also speaks to the underappreciated influence that sisters often have in autocratic families with a succession of male leaders, like the Kim family that has ruled North Korea for three generations.

We think of the North Korean system as a dictatorship, in which one man holds ultimate power, but it is more appropriate to think of it as a royal dynasty, with all the problems of succession and internal competition inherent to such regimes — and this is what gives Kim Yo Jong such a prominent place in her brother’s regime. In this, North Korea shares features with medieval European monarchies. In medieval Spain, sisters wielded significant power, played key diplomatic roles and helped ensure the stability of the king’s rule. A comparison between the two helps to understand the power dynamics in North Korea, ones that the strict censorship of information has made it difficult for Westerners to understand.

When King Fernando of León-Castile died in the 11th century, his kingdom was partitioned into three: one region for each of his three sons, Sancho II, Alfonso VI and García. But King Fernando also had two daughters, royal sisters Urraca and Elvira Fernández. For their inheritance, they received all the monasteries in the kingdom, giving them a territorial power base that extended across their brothers’ domains.

As their brothers jockeyed for power, the sisters played a key role. Initially they sided with Sancho II and Alfonso VI, displacing García from his kingdom and sending him into exile in Muslim Spain. Then Sancho II rose against Alfonso VI, and Alfonso, too, went into exile.

After Sancho II died under suspicious circumstances while besieging Urraca in her city of Zamora, she summoned Alfonso VI back and helped him claim the kingdom their father had held. Urraca used her extensive property holdings to prop up his fledgling rule, for instance, by using them to re-found a bishopric in a city that had been in the territory of one of his brothers. Early documents from his reign describe him as ruling “together with the consent of Urraca.”

Urraca and Elvira signed more than half of the documents the king issued during the rest of their lifetimes, a higher percentage than any of his nobles or counselors, which lent their weight and prestige to his decisions. Unlike his nobles and his male family members, Alfonso’s sisters’ power, because of their gender, rested only in their relationship to the ruler. This made them people he could trust, people whose allegiances were only to him.

These alliances within a dynasty have less to do with the personalities or inherent affections of the individuals involved and more to do with the way power was organized in medieval Spain, and seems to be arranged today in North Korea. In both cases, what appears to be the unitary and secure rule of a single male leader is in fact undergirded by the support or at least acquiescence of those closest to him, and the capacity to eliminate those who do not acquiesce.

The brutality of Kim Jong Un’s regime stems in part from its inherent instability. Kim Jong Un stands at the apex of power in North Korea, but like Alfonso VI centuries earlier, his power depends on the ongoing acceptance of his rule by an elite who are also his main competitors for power — a group that includes members of his own family, primarily men. This competition can be fraught: Last year, Kim Jong Un’s older half-brother, Kim Jong Nam, was apparently assassinated in Malaysia.

Kim Yo Jong’s prominence in the North Korean Olympics delegation is matched by her role within her brother’s regime. She has held an important position in the Propaganda and Agitation Department of the North Korean Workers’ Party since 2014, and last year was elevated to the Politburo as an alternate member. But these official positions are surely reflections of her power, not the root of it. For that, we need to look to her relationship with her brother.

Kim Yo Jong’s actions match those of her medieval predecessors. She puts a friendly, feminine face on the regime for public consumption, which softens its image — as illustrated by the fawning by media over Kim Yo Jong that produced so much backlash over the past few days. She is reported to have filled in for her brother when he was ill in 2014, something royal sisters in medieval Spain did regularly.

In a medieval world in which communications were difficult, a royal sister also often acted as the king’s hand when he was far away, and they were perceived as intercessors who could advocate for their allies and mitigate the harshness of the king’s judgments.

All of these actions help boost the regime and maintain Kim Jong Un’s grip on power. Kim Yo Jong may not have come across as a menacing, powerful figure, but like her medieval predecessors she probably wields as much influence as anyone in North Korea, short of Kim Jong Un.

The role of a sister is fraught, then and now. Kim Yo Jong might continue to bolster her brother’s regime or might be called upon one day to adjudicate between claimants to power in North Korea, as medieval royal sisters often were. Will she rule North Korea in her own right, as Alfonso VI’s daughter would do one day, claiming the throne of Leon and Castile upon his death? Could that prospect eventually jeopardize her position — and her safety — by making her more of a threat to the dictator’s power? Time will tell.