In Game of Thrones season 1, episode 7 "You Win or You Die," Lord Eddard Stark confronts Cersei Lannister about the nature of her and her twin brother, Jaime Lannister's relationship. Without any shame, Cersei responds by pointing out that the Targaryens had practiced sibling marriages for centuries to preserve their bloodline. This remark prompts Ned to consider their relationship in a different light.
Cersei's statement holds some truth, as the upcoming prequel to Game of Thrones - House of the Dragon (2022) - showcases Viserys I Targaryen's second wife, Alicent Hightower, who arranges a marriage between her son, Aegon, and her daughter, Helaena, in keeping with the Targaryen tradition. This raises the question of why Cersei and Jaime's relationship was deemed taboo in Game of Thrones, when Aegon II of House of the Dragon had simply fulfilled his duty by marrying Helaena.
The Faith Militant Uprising
The secret behind House Targaryen's enduring Valyrian lineage lies in their age-old tradition of intermarrying siblings. As descendants of the Valyrian Freehold, the ruling dynasty of Westeros, it is no wonder that the Targaryens were known as the Blood of Old Valyria. Before the Valyrian Freehold met its fiery end, the Valyrians, including one of the great dragonlord families, regularly engaged in these types of unions to preserve their distinctive features.
This practice sheds light on why Aegon the Conqueror, the legendary ruler, married his elder sister Visenya. It was a duty-bound decision aimed at securing his succession. Additionally, Aegon's deep affection for his younger sister Rhaenys led him to take her as his second wife. The bond between these sister-wives proved vital during the conquest of Westeros, resulting in the birth of two sons: Aenys I from Rhaenys and Maegor I from Visenya.
Although Aegon adeptly managed the Faith's reservations with tact and sensitivity, his son Aenys, who ascended the Iron Throne after him, lacked finesse in handling such matters. Aegon the Conqueror was amicable towards the Faith of the Seven, and due to House Targaryen's extensive conquests in Westeros along with their possession of powerful dragons, the opinions of the High Septons were silenced. The Faith chose to turn a blind eye to the situation, neither condemning nor supporting Aegon's multiple marriages. However, there were devout members of the Faith who strongly believed that Aegon's unions went against the rules and principles of their faith.
Aegon and Rhaenys' son, Aenys I, entered into a marital union with his cousin Alyssa Velaryon, resulting in the birth of six offspring. Their eldest child, a daughter named Rhaena, held a significant position in the line of succession. Visenya, Aenys, and Alyssa were initially opposed to the idea of marrying Maegor, their son, to Rhaena in order to secure his claim to the throne. The High Septon, Aenys, and Alyssa contested this proposition. Maegor's first spouse was Lady Ceryse Hightower, who happened to be the niece of the High Septon. Due to her inability to conceive, Maegor sought a second partner - Lady Alys Harroway. This second marriage caused a stir throughout the Seven Kingdoms, and many individuals expressed their disapproval. Despite their unsuccessful attempts to persuade the Septon at Dragonstone to officiate the wedding, Maegor and Alys proceeded to hold a Valyrian ceremony, which was overseen by his mother, the Dowager Queen, Visenya. Although Aenys opposed the union, Ser Martyn, Ceryse Hightower's brother, insisted that Maegor dismiss his second wife. The High Septon declared the marriage as sinful. Unyielding, Maegor maintained that the laws of the Faith did not apply to those with dragon blood. As a result, he faced a five-year exile while Aenys confronted the militant uprising of the Faith.
King Jaehaerys' Doctrine of Exceptionalism
The military order of the Faith rose up against House Targaryen in a powerful and united rebellion after Aenys married his son to his daughter. This union, officiated by Septon Murmison, was met with extreme opposition from the Faith Militants, who not only killed the septon but also persecuted the lords who supported the king. The High Septon publicly denounced the Targaryens, igniting a prolonged conflict that would persist until the wise reign of the fourth Targaryen king, Jaehaerys I.
Although Aenys was initially overwhelmed by the uprising, he managed to escape King's Landing and seek refuge at Dragonstone, where he eventually passed away. His half-brother, Maegor, seized the throne from Aenys' children and, in a bold move, invited the Faith Militants to a Trial of Seven, which they accepted. Legend has it that Maegor emerged as the sole survivor of this fateful trial, solidifying his claim to the throne.
Wasting no time, Maegor swiftly mounted Balerion, his fearsome dragon, and unleashed a fiery assault upon the Sept of Remembrance, obliterating it and engulfing hundreds of Faith Militants in the inferno. This act of brutality further escalated the conflict between Maegor and the Faith, pushing it into an intractable state. The truth was, no one knew how to effectively address the concerns and grievances of the Faith until the arrival of the wise and renowned ruler, Jaehaerys.
Aenys's son, King Jaehaerys I, followed in his grandfather's footsteps as a skilled diplomat. According to House of the Dragon, he ruled for almost sixty years, during which he prioritized the restoration of peace within the realm. One of his major accomplishments was reconciling the crown and the Faith, leading to certain rights being granted to House Targaryen. A significant aspect of this agreement was that as long as the Targaryens defended the Faith, the Faith Militant would no longer exist. This became a cherished tradition for the Targaryens. Additionally, it was decided that any remaining members of the Faith Militant would be pardoned if they relinquished their weapons. Considering the weakened state of the armed rebellion at that time, Jaehaerys' accord with the Faith Militant was deemed generous.
Both sides upheld their agreement, resulting in the Faith Militant remaining dormant for the next three centuries, with the crown assuming the responsibility of protecting and preserving the Faith. As a result, the descendants of the Wise King, Rhaenyra and Daemon, were able to marry in a Valyrian ceremony, as depicted in House of the Dragon. However, this union was seen as a sin by the Faith and an illicit practice in the Seven Kingdoms. Additionally, the negative consequences of such marriages, particularly the prevalence of genetic illnesses, persisted among the members of House Targaryen. Due to their frequent inbreeding, the Targaryens gained a notorious reputation for having mental instability. This is exemplified by the well-known saying, "Every time a Targaryen is born, the Gods flip a coin," highlighting the high likelihood of Targaryens eventually succumbing to madness, as demonstrated by the character Daenerys Targaryen in Game of Thrones.