Aegon V (Egg)'s Search for Dragonlore/Prophecy

"Someday the dragons will return. My brother Daeron's dreamed of it, and King Aerys read it in a prophecy. Maybe it will be my egg that hatches. That would be splendid." -The Mystery Knight

It is well known that Egg decided he needed dragons to enforce the reforms he wanted to make as a ruler. This obsession resulted in the death/ritual/sacrifice/sorcery at Summerhall. Egg (like some Targaryens before and after him) was driven by prophecy, and I wanted to explore/look at the time period before Summerhall (late 250's AC) and see what he was doing in relation to this.

As he grew older, Aegon V had come to dream of dragons flying once more above the Seven Kingdoms of Westeros. In this, he was not unlike his predecessors, who brought septons to pray over the last eggs, mages to work spells over them, and maesters to pore over them. Though friends and counselors sought to dissuade him, King Aegon grew ever more convinced that only with dragons would he ever wield sufficient power to make the changes he wished to make in the realm and force the proud and stubborn lords of the Seven Kingdoms to accept his decrees. -TWOIAF, The Targaryen Kings: Aegon V

If interested: The Blood of Old Valyria Part V: How to Build a Dragon (Attempts to bring back dragons)

Background

Like his brother Aemon, Egg grew up never expecting to be in play for the throne, but the king at the time (Aerys I) and hand (Bloodraven) were both deeply interested in arcane maters/the higher mysteries.

It has been suggested by some that a likelier cause for Bloodraven's rise to power was the fact that Aerys's interest in arcane lore and ancient history matched that of Rivers, whose studies of the higher mysteries were an open secret at the time. Bloodraven had already risen to prominence at the court, but few expected that Aerys would name him Hand. When he did, it kindled a quarrel between the king and his brother, Prince Maekar, who had expected the Handship to come to him. Thereafter Prince Maekar departed King's Landing for Summerhall for years to come. -TWOIAF: The Targaryen Kings: Aerys I

If interested: Characters Who Have Dabbled in the "Higher Mysteries"

Grand Maester's Deaths (Kaeth/Ellendore)

While likely a coincidence (and due to old age), the rigors of the job of grand maester killed 2 men within a year during the late 250's AC. Its possible that Egg was working them to death having them searching for arcane knowledge, etc.:

"I was but two-and-forty when the Conclave called me. Kaeth was eighty when they chose him, and Ellendor was nigh on ninety. The cares of office crushed them, and both were dead within a year of being raised. Merion came next, only six-and-sixty, but he died of a chill on his way to King's Landing. Afterward King Aegon asked the Citadel to send a younger man. He was the first king I served." -AFFC, Cersei VIII

Commissioned Journeys for Dragonlore

Egg sent men on (rather expensive) journeys to search for dragonlore:

The last years of Aegon's reign were consumed by a search for ancient lore about the dragon breeding of Valyria, and it was said that Aegon commissioned journeys to places as far away as Asshai-by-the-Shadow with the hopes of finding texts and knowledge that had not been preserved in Westeros. -TWOIAF, The Targaryen Kings: Aegon V

Worth noting:

In what place, if any, has there been an accumulation of dragonlore?

GRRM: Valyria. The Citadel. Dragonstone. Probably some of the Free Cities as well. Maybe Asshai in the far east. -SSM, Dragonlore: 19 May 2000

also potentially in Volantis:

Tyrion had read much and more of dragons through the years. The greater part of those accounts were idle tales and could not be relied on, and the books that Illyrio had provided them were not the ones he might have wished for. What he really wanted was the complete text of The Fires of the Freehold, Galendro's history of Valyria. No complete copy was known to Westeros, however; even the Citadel's lacked twenty-seven scrolls. They must have a library in Old Volantis, surely. I may find a better copy there, if I can find a way inside the Black Walls to the city's heart. -ADWD, Tyrion IV

If interested (basically Young Griff has a ton of info on how to ride a dragon): Tyrion, Dragonlore & the Golden Company

Summerhall

This all culminated at Summerhall where numerous people died due to Egg's "attempt":

What became of the dream of dragons was a grievous tragedy born in a moment of joy. In the fateful year 259 AC, the king summoned many of those closest to him to Summerhall, his favorite castle, there to celebrate the impending birth of his first great-grandchild, a boy later named Rhaegar, to his grandson Aerys and granddaughter Rhaella, the children of Prince Jaehaerys. -TWOIAF, The Targaryen Kings: Aegon V

If interested: The Leadup to the Tragedy of Summerhall

Also worth noting that "dreams of dragons" killed every single one of Maekar's sons: My Brothers Dreamed of Dragons too, and the Dreams Killed Them, Every One

TLDR: Before the actual events of Summerhall, Egg's desire for dragons potentially worked two elderly grand maesters to death, commissioned expensive journeys in search of dragonlore (potentially inadvertently aiding Young Griff/the Golden Company in the process) likely due to the same prophecies (Daenys the Dreamer) that have affected other Targaryens before and after him.