Dragonpit Summit

"There's only one war that matters. And it is here."

- Jon Snow

The Parley in King's Landing is a gathering of the four major monarchs of Westeros in King's Landing to discuss the future of the Seven Kingdoms after Daenerys Targaryen's invasion of Westeros comes to a stalemate and an armistice proposed by Lord Tyrion Lannister is agreed upon.

In the past, "Great Councils" have been convened to discuss the future of the realm when the line of succession of the monarchy and inheritance of the Iron Throne is unclear.

Cersei Lannister holds the crown after the collapse of the Baratheon dynasty, claiming it by right of conquest. Daenerys Targaryen claims the Iron Throne on the basis that it belongs to the once royal House Targaryen, which was overthrown by House Baratheon in the war known as Robert's Rebellion.

Jon Snow, who is said to be a bastard of House Stark, rules the Kingdom of the North as the King in the North, though he has become an ally of Daenerys Targaryen. He seeks to use the gathering to provide proof of the existence of the Night King and the White Walkers through a captured wight.

Euron Greyjoy sits on the Salt Throne, the throne of the Kingdom of the Iron Islands, as the King of the Iron Islands, though he has since allied with the now royal House Lannister. His hold of the Salt Throne is disputed by his niece and nephew, Yara and Theon, the former who is now a prisoner of Euron, and both of whom are allies of Daenerys Targaryen.

Prelude
Robert's Rebellion saw the ousting of the Targaryen dynasty that had ruled the unified Seven Kingdoms of Westeros since the Targaryen Conquest nearly three centuries prior. However, civil war broke out in the form of the War of the Five Kings after the death of Robert Baratheon as three kings claimed the Iron Throne while two others attempted to secede from the Seven Kingdoms.

The War of Five Kings greatly weakened the Baratheon dynasty, which had become a puppet of House Lannister after Robert's death through the reigns of his alleged sons, Joffrey and Tommen, who were actually bastards born of incest between Robert's wife, Cersei Lannister, and her twin brother, Jaime Lannister. They passed off Joffrey, Tommen, and Myrcella as Robert's children to keep them alive.

Eventually, Cersei herself ascended to the Iron Throne after destroying her gathered enemies - the Faith Militant and House Tyrell - at the Great Sept of Baelor. The event inadvertently killed her last surviving child, Tommen, thus ending the Baratheon dynasty and leaving a power vacuum that Cersei took advantage of, claiming the crown for herself and beginning the Lannister dynasty. However, war had not ended in Westeros: Daenerys Targaryen gained allies in the enemies that Cersei had made in the Reach and Dorne, two of the Seven Kingdoms, and began her invasion of Westeros to restore her family dynasty.

Euron Greyjoy had become King of the Iron Islands after murdering his brother, Balon Greyjoy. After Balon's children, Yara and Theon Greyjoy, beat him to forming a pact with Daenerys, he instead allied with Cersei.

Jon Snow, former Lord Commander of the Night's Watch, had become King in the North after defeating House Bolton at the Battle of the Bastards, avenging the Red Wedding which had seen the deaths of Robb Stark and many of his Northern and Riverland bannermen. Jon Snow's time in the Night's Watch revealed to him that an ancient threat to all of humanity had returned after 8,000 years: the White Walkers. The Night King led the White Walkers on a crusade beyond the Wall to massacre the Free Folk and reanimate their corpses as wights, adding them to his army of the dead. Jon mobilized the North and the Vale to prepare for the coming Great War against the White Walkers and the return of the Long Night, a dark and terrible winter that lasted for over a generation when the White Walkers first descended upon the world.

However, because the White Walkers had been gone for thousands of years, they had faded into legend: most in northern Westeros had believed that they were extinct (prior to Jon Snow's coronation as King in the North), while everyone else believed that the White Walkers never existed in the first place and were simply tales and folk legends. With the Seven Kingdoms preoccupied with their own civil wars, Jon Snow sought to take advantage of the rare summit by gathering proof of the return of the White Walkers: by capturing a wight at the Wight Hunt beyond the Wall. With a band of his followers, Jon Snow and his men were able to capture a wight beyond the Wall near Eastwatch-by-the-Sea, though they lost many men as well as one of Daenerys Targaryen's dragons, Viserion, who had, unbeknownst to them, been resurrected by the Night King.

The parley
To be added

Aftermath
To be added

In the books
In the A Song of Ice and Fire novels by George R. R. Martin, the event has yet to occur. Given that the TV show has surpassed the books, it is unclear if the Parley in King's Landing will be convened at all, and under what circumstances it will be if it is. In the past, Great Councils have been convened to discuss the future of the Seven Kingdoms of Westeros when the line of succession for the Iron Throne was being disputed among House Targaryen, the royal family. This great parley seem to differ from the traditional Great Councils, however.