|Although this article is based on canonical information, the actual name of this subject is pure conjecture.
The Great Council of 305 AC took place following the Assassination of Daenerys Targaryen, and was originally convened to decide the fates of Tyrion Lannister and Jon Snow. With no monarch to render a verdict, the council was made up of the heads of each surviving great house of Westeros, along with other key players from the Battle of King's Landing.
Events of the Great Council
Following the assassination of Daenerys, both Jon and Tyrion were kept as prisoners by the Unsullied, soldiers loyal to Daenerys Targaryen and her cause, and who continued to control King's Landing after its sacking. When news of the events reached Sansa Stark in Winterfell, she journeyed south with her brother Bran and her sworn sword, Brienne of Tarth. Samwell Tarly, who was last seen at Winterfell with Gilly and her son, also journeyed south. Other lords and ladies had arrived in King's Landing as well to discuss the fate of Jon and Tyrion, and to decide the political future of Westeros.
Election of Bran Stark
- "There's nothing in the world more powerful than a good story, nothing can stop it, no enemy can defeat it, and who has a better story than Bran the Broken?"
- ―Tyrion Lannister to the assembled lords at his trial
Daenerys's assassination had left the realm without a clear leader. Although this had essentially been the case for the previous six years - with the War of the Five Kings and the other conflicts that came afterwards - the near-extinction of three great houses (Targaryen, Baratheon, and Lannister) had created huge uncertainty about who should inherit the throne.
Members of the Great Council proposed three options for settling the succession:
- Edmure Tully, Lord of Riverrun, set himself forward as a candidate for the crown, citing his battle experience as a veteran of two wars, as well as his experience with statecraft as credentials. This suggestion was promptly quashed by his niece, Sansa Stark, who sternly told her uncle to resume his seat.
- Samwell Tarly, who had served in the Night's Watch, suggested that all the people of Westeros select their own monarch, allowing each individual one vote in a democratic system (similar to the Choosing of Lord Commanders in the Watch, and a system that Tyrion had previously mentioned to Daenerys herself). This idea resulted in mocking laughter from the assembled lords and was quickly rejected as well.
- Finally, Tyrion suggested the idea of an elective monarchy, where the lords and ladies of the realm would congregate at the Dragonpit in King's Landing to determine a new king or queen following the death of the previous one (somewhat similar to the Kingsmoot ceremony of the Iron Islands, which Tyrion had also mentioned to Daenerys). This would also remove the possibility of unskilled or inexperienced leaders inheriting the throne. Tyrion claimed that nothing was better at uniting disparate people than a good story, and for that reason he suggested as monarch Brandon Stark, for his story of survival against extreme odds, and his abilities as the Three-eyed Raven and keeper of the world's memory. Naming him "Bran the Broken" - for his inability to walk - Tyrion's idea was swiftly appreciated and accepted by the members of the council.
Despite the support gained for Brandon Stark, his sister Sansa was the only assembled member who did not immediately accept his crown. Saying that the Northmen had suffered too much to ever accept the rule of an outsider again (as could well happen in the future with an elective monarchy), she demanded that the North once again become its own sovereign kingdom, "as it was for thousands of years." This was granted by Brandon, who was thereafter hailed as Bran the Broken, First of His Name, King of the Andals and the First Men, Lord of the Six Kingdoms, and Protector of the Realm.
Secession of the North
- "I love you, little brother, I always will. You'll be a good king. But tens of thousands of northmen fell in the Great War defending all of Westeros, and those who survived have seen too much and fought too hard ever to kneel again. The North will remain an independent kingdom, as it was for thousands of years."
- ―Sansa Stark to Brandon
Robb Stark's war for independence would be successful until he broke his betrothal with Roslin Frey to marry Talisa Maegyr, a Volantene noblewoman whom he had met on the campaign. As a result, Lord Walder Frey (Roslin's father) orchestrated the Red Wedding with Tywin Lannister, a successful massacre of the northmen that dined within his halls when Edmure Tully was married to Roslin instead. Both Robb and his mother Catelyn Tully were killed, intensifying the Stark-Lannister blood feud. Following the Red Wedding, Roose Bolton was named as Lord Paramount of the North and Lord of Winterfell, replacing the Starks and earning the loathing of many northern houses, whose banners had been pledged to the Stark cause.
Roose would later be murdered in a conspiracy by his legitimized bastard son, Ramsay Bolton, who would continue to rule the North through fear tactics and brutal violence. Eventually, Jon Snow -- the purported illegitimate son of Ned Stark -- and Sansa Stark marched south from Castle Black to take back Winterfell. The bulk of Jon's forces consisted of the Free Folk, and he had only managed to obtain the support of House Mormont as well as other minor houses, as larger houses were unwilling to fight alongside wildlings.
With the threat of the Army of the Dead looming, Jon Snow, crowned King in the North by the Northern lords, sought an alliance with Daenerys, with whom he quickly fell in love. From Dragonstone, Jon brought Daenerys and her forces back to Winterfell in preparation for the war against the dead after pledging allegiance to Daenerys as queen.  However, the northerners still maintained a residual distrust of House Targaryen after the brutal torture and murder of Brandon Stark and Rickard Stark by Daenerys's father twenty years prior. After the Great War, both the northmen and Daenerys's forces suffered great casualties. Because the North became a vassal to Daenerys when Jon bent the knee to her, their forces were pledged to help her take the Iron Throne from Cersei Lannister. Daenerys opted to take the Iron Throne from Cersei immediately against Sansa's advice that they wait a period of time until their forces had recovered.
Eventually, after the Battle of King's Landing and the conclusion of the Great Council, Brandon Stark's selection as King of the Andals and the First Men would finally allow Sansa to achieve legal independence for the North as a recognized polity, free from what was now the Six Kingdoms.
Judgment on Tyrion and Jon
Both Tyrion and Jon had recently been convicted of crimes, and the council was originally convened to decide their punishments: Tyrion had been arrested on the orders of the late Daenerys for treason, due to freeing his brother from the Unsullied's custody; Jon was imprisoned for assassinating Daenerys, following her razing and massacre of King's Landing - she had made plans do the same in future conquests, and he was attempting to prevent further massacres. Grey Worm, commander of the Unsullied and one of Daenerys's greatest supporters, was particularly keen to seem them punished.
After Brandon Stark was named king by his peers, he pardoned Tyrion and named him Hand of the King (a position Tyrion had previously held under Joffrey Baratheon and Daenerys herself). Grey Worm protested against this, and Tyrion initially rejected the position, saying that he had made too many mistakes in the past to be useful or worthy of the post. Bran acknowledged this, and made it clear that as his Hand, Tyrion would spend the rest of his life fixing the mistakes he made. Jon was later exiled to the Wall as a member of the Night's Watch, in order to prevent a war between the Unsullied and Jon's supporters. Grey Worm accepted this punishment for him, as did Sansa and Arya.
Under the rule of Brandon Stark, there was much to be rebuilt and reorganized across Westeros: Ser Bronn of the Blackwater, a former sellsword and close companion of both Tyrion and Jaime, was named Lord Paramount of the Reach and Lord of Highgarden, fulfilling the reward of his own castle that had long been promised to him by the Lannisters. Tyrion was allowed to remain as Lord of Casterly Rock, a title that his father, Tywin, had disinherited him from on account of his dwarfism and promiscuity. Daenerys had already granted independence to Yara and the Iron Islands, and as Robin Arryn and the Prince of Dorne had supported Bran's ascension to the throne, it can be assumed that they remained the rulers of their respective regions and did not make any bids for independence on a similar note to Sansa, despite their long-standing divisions with the throne.
In addition to Tyrion's appointment as Hand of the King, the following nobles were granted seats on the small council by Brandon:
- Lord Bronn, as Master of Coin.
- Lord Davos Seaworth, as Master of Ships.
- Ser Brienne of Tarth, as Lord Commander of the Kingsguard.
- Samwell Tarly, as Grand Maester.
The small council informed Brandon that they would present him with suitable candidates for the positions of Master of Whisperers, Master of Laws, and Master of War. Both the North and the Kingsguard came to possess their first female leaders, with Queen in the North Sansa Stark enjoying great harmony with the south on the account of her and Bran's kinship. This put an end to the long-standing rivalry between the two realms proliferated by the War of the Five Kings. Brandon's reign also saw the induction of Podrick Payne as a knight of the Kingsguard.
It was the first formal election of an absolute monarch in the history of Westeros (although different methods of deciding succession had been debated by other Great Councils in the past), and saw the reorganization of the Seven Kingdoms into an elective monarchy.
In the books
In the A Song of Ice and Fire novels, no equivalent event has occurred. The TV show has surpassed the timeline of the books, so it is unclear if an equivalent event will occur.