- This article is about the character during the Faith Militant uprising. For the title see High Septon (title).
- "One morning, Maegor was found dead on the Iron Throne. No one knows how. Maegor's cruelty died with him. His successor saw the wisdom of a united crown and faith, and his Hand reached an accord with the High Septon. As long as the Iron Throne defended the Faith, the Faith would put aside its own swords... and its condemnation of the Targaryens. Perhaps the High Septon felt he had no course but compromise."
- ―The High Sparrow
This High Septon held the position during the reign of King Aenys Targaryen.
After Aegon I Targaryen conquered and united the Seven Kingdoms (except for Dorne) in the Targaryen Conquest, the High Septon at the time - after much prayer - decided to accept his new reign, and personally anointed and crowned Aegon as Lord of the Seven Kingdoms. Yet while the Targaryens had nominally converted to the Faith of the Seven, the dominant religion in Westeros, they never wholly accepted it - specifically, the Faith's strict condemnation of incest, which it held to be an abomination. The Targaryens had incestuously married brother to sister for generations (whenever possible) to "keep the bloodline pure", in the custom of their Valyrian ancestors. For that matter, Aegon I broke not only the Faith's rules against incest, but its rules against polygamy, as he was married to both of his sisters at the same time: Queen Visenya and Queen Rhaenys.
The Faith wasn't in much position to challenge the victorious Targaryen army after the Conquest or their massive dragons, but Aegon I was wise enough to tread lightly with the Faith: both sides tacitly agreed that the Targaryens' incestuous marriages were a relic of their past, which would soon fade. Aegon I didn't intend for future generations of his new dynasty to continue to have incestuous marriages, and in return, the Faith didn't press the matter for the remainder of his life. Aegon I eventually died and was succeeded by his elder son, Aenys I Targaryen, his only child by his sister-wife Rhaenys.
To the surprise of all, however, later in his reign King Aenys tactlessly wed his daughter to his own son. The incestuous marriage of Princess Rhaena and Prince Aegon broke the Targaryens' prior promise to the Faith, which could stand the abomination no longer. The new High Septon led the denunciation of the Targaryens, and the military order of the Faith of the Seven, the Faith Militant, rose up in open revolt.
In the books
In the A Song of Ice and Fire novels, this High Septon was originally a member of House Hightower, though his name was eventually forgotten as High Septons abandon their real names once they rise to the position. However, he is known to have been the uncle of Ceryse Hightower and the brother of Martyn Hightower, Lord of Oldtown, and Ser Morgan Hightower, Commander of the Warrior's Sons (the senior order of the Faith Militant).
He was the High Septon during the reigns of Aenys Targaryen and Maegor Targaryen. At the height of the Faith Militant uprising, before Maegor retook King's Landing, this High Septon was functionally the ruler of the Seven Kingdoms for some months - foreign officials such as from the Iron Bank of Braavos, when asking for the king of the realm to treat with, were told to seek out the High Septon and not Aenys.
He died mysteriously in 44 AC, though his death and the election of a new more passive High Septon did not end the uprising. Many think that the High Septon was actually poisoned, probably by Maegor's agents - though some suspect that it was actually his own brother Morgan Hightower, because Maegor was on the verge of destroying Oldtown but the High Septon would never yield to him, even if it meant nothing would be left of the city, its people, and its knowledge but ash. Evidence supporting this theory is that Morgan Hightower was the only member of the Warrior's Sons that Maegor ever pardoned.