Jaehaerys was the third son of King Aenys I, and upon Aenys I's death in 42 AL his half-brother Maegor I took the crown, rather than Jaehaerys older brother Aegon. Maegor usurped the crown and personally killed Aegon, while he, his mother Alyssa Velaryon and Alysanne were prisoners in Dragonstone, but managed to escape once his great-aunt Visenya passed away. The escape tragically provoked Maegor to torture to death Viserys, Jaehaerys other brother, but his mother nonetheless rallied several lords in order to support his claim.
Jaehaerys I took the throne in 48 AL upon the death of his uncle, and his mother was his Regent for two years. Whilst Maegor the Cruel had brutally suppressed the Faith of the Seven during the uprising, Jaehaerys adopted a path of negotiation, his friendship with Septon Barth helping him understand the Faith. In return for the Faith's surrender and the disbanding of its militant orders, the Warrior's Sons and Poor Fellows, the Faith would suffer no further oppression and the Targaryens would return to being their staunch supporters. However, Jaehaerys also made it clear that the Targaryens would continue to be unbound by the laws and morality of mainstream Westeros when he married his sister, Alysanne. The Faith agreed to these terms. For ending the war peacefully and restoring the relations of the crown and church, Jaehaerys was dubbed 'Jaehaerys the Conciliator'.
Jaehaerys ruled for fifty-five years, more than any other king in modern history, outliving two of his sons and heirs; Aemon and Baelon. Unfortunately, of the thirteen children he and Alysanne ever had, only nine lived into adulthood. In later life Jaehaerys also became known as the 'Old King', but this was meant respectfully. He set to work on many great deeds and was a skilled negotiator and peace-maker. He and his sister-wife Alysannae worked as a formidable team, setting the realm to rights and ending outdated practises (such as the old tradition of first night). Alysannae was also a great believer in the Night's Watch, and at her urging Jaehaerys supported the Watch, sending them more men and helping reinforce the castles along the Wall, as well as funding the construction of Deep Lake castle to replace the Nightfort when it was abandoned. Alysanne was also a great supporter of the commons, sponsoring many charities to help the lot of the smallfolk.
Jaehaerys and Alysanne were beloved by the people and respected by the nobility for restoring Westeros to peace and plenty after decades of turmoil and war.
After his two eldest sons Aemon and Baelon died before him, he called for a council and chose his grandson Viserys, Baelon's eldest son, as heir, passing over his granddaughter Rhaenys, Aemon's daughter, and Rhaenys' seven year old son Laenor.
Tragically Queen Alysanne died of grief a year after the suicide of their youngest child, Princess Gael. With the death of his beloved wife and son Baelon, Jaehaerys spent the last few years of his reign bed ridden, while his new Hand Otto Hightower ruled the realm, and Otto's daughter Allicent looked after him. Upon Jaehaerys' death, he was succeeded by his grandson Viserys.
He rode the mighty Dragon Vermithor, nicknamed the Bronze Fury, and the beast refused to be ridden after the death of the king, remaining in a semi-wild state for decades, until he was finally re-tamed and perished in the Dance of Dragons. He flew several times to aid the Night's Watch against the wildlings.
Character and appearance
Jaehaerys I Targaryen is mostly remembered and depicted in old age. At this time he had the appearance of old, dignified wisdom. He was elderly but unstooped, and very tall. He had an impressive white beard that reached to his waist and preferred to wear flowing robes of black and gold. Typical of his house, his eyes were purple, and as a youth he was very handsome. He had a new crown commissioned, a simple gold band set with seven gemstones of different colours, as opposed to wearing the warlike crown of his grandfather and uncle. He typically did not wield a sword, though he was exceptionally skilled with both blade and lance - he saw this as a way of avoiding the mistake that his father made, of being viewed as weak. He was a proven warrior, battle tested and very confident. Jaehaerys was beloved by his descendants, and brought abundance to all of Westeros in his reign, which his grandchildren would rather unfortunately bring disarray to with the Dance of the Dragons.
Jaehaerys, starkly unlike either of his predecessors, was both a careful thinker, a planner and a diplomat. He was courteous but firm, resolute but not unyielding to argument. He cared fiercely for the people of Westeros, but was not a dreamer like some of his successors - he was not blinded by delusions of conquest, greatness or might, and lacked the Targaryen madness that seemed to plague his family. His plans were realistic and achievable, even when generous - he built the Kingsroad, among other roads to ease transport throughout the Seven Kingdoms, as well as abolishing the right to first night with the persuasion of his queen. He deeply loved his wife Alysanne, his closest confidante, thought they quarrelled ferociously on occasion. He loved her so much that he was truly broken by her death, as well as that of his son Baelon, leaving him a broken shell of a man. It is known that he had one of the healthiest relationships with his spouse than most of the Targaryens - he never took any mistresses, as Maegor the Cruel, Aerys the Mad and Aegon the Unworthy did.
Jaehaerys was a great king, perhaps the greatest of all the Targaryen kings, and reigned the longest out of all of them - even after the Targaryens were extinguished, he is considered the mightiest and wisest monarch who ever lived, though not all of his reforms remain by the time of the War of the Five Kings. He faced few, if any rebellions, and his reforms, policies and achievements were applauded and fondly remembered by all of Westeros. It is worth noting that one of Jaehaerys' most infamous decision was to choose Septon Barth, a commoner he befriended in the library of the Red Keep, as Hand of the King - a post traditionally afforded to noblemen - in recognition of the man's brilliance and wisdom. He sent Barth to Oldtown to reconcile with the Faith, as opposed to bringing war upon them. Barth and Jaehaerys worked together to forge peace throughout the Seven Kingdoms. After he died, even the inhabitants of Dorne (where the Targaryen rule was not absolute) mourned for him.