Warning: This article contains spoilers for A Knight of the Seven Kingdoms Episode 3.
A Knight of the Seven Kingdoms Episode 3 established a direct connection between the young squire, Egg (Dexter Sol Ansell), and the Targaryen ruler known as the Mad King. The new HBO show is based on George R.R. Martin's novellas, Tales of Dunk and Egg, and takes place after House of the Dragon, but before Game of Thrones. Once again, the Targaryens are at the centre of the drama in A Knight of the Seven Kingdoms, particularly following the revelation in the third episode that Egg is actually Aegon V Targaryen.
The reveal of Egg's heritage came shortly after Ser Duncan (Peter Claffey) and Egg, posing as his squire, came across a fortune teller who promised to reveal their futures. In Egg's case, the fortune teller told him he "would be king," and "die in a hot fire." Interestingly, the seer also said everyone would "rejoice in [Egg's] dying:"
"You shall be king, and die in a hot fire, and worms shall feed upon your ashes. And all who know you shall rejoice in your dying."
While Dunk took this as a joke, the prophecy shook Egg, particularly as he was still hiding his Targaryen lineage at the time. One thing audiences may notice about the prophecy is that it seems to resemble traits of another famous Targaryen King: the Mad King.
When Game of Thrones begins, it comes a decade or so after the death of the Mad King, who was killed during Robert's Rebellion and eventually replaced by Robert Baratheon on the throne. It was well known that the Mad King had an obsession with wildfire, a bright green chemical fire that burns hotter than the average flame. He had plans to burn the city of King's Landing to the ground rather than hand it over to Robert Baratheon, which is why Jaime Lannister, his sworn Kingsguard, killed him.
Jaime Lannister: "You’ve heard of wildfire? The Mad King was obsessed with it. He loved to watch people burn, the way their skin blackened and blistered and melted off their bones... He burned anyone who was against him. Before long, half the country was against him. [The King] saw traitors everywhere, so he had his pyromancer place caches of wildfire all over the city, beneath the Sept of Baelor and the slums of Flea Bottom. Under houses, stables, taverns. Even beneath the Red Keep itself. Finally the day of reckoning came... I came to the King, begging him to surrender. He told me to bring him my father’s head. Then he turned to his pyromancer. 'Burn them all,' he said."
The fortune teller's prophecy in A Knight of the Seven Kingdoms references a death in a hot fire, and the people rejoicing in Egg's death, which seems to suggest he could go on to become the Mad King. However, the Targaryen history is more complex, and while Egg is connected to the Mad King, he does not become the Mad King.
How Are Egg and the Mad King Connected in Game of Thrones?
Episode 3 of A Knight of the Seven Kingdoms confirms that Egg is secretly Aegon V, the son of Maekar I. He and his brothers, Aerion, Daeron, and Aemon, are all descendants of Rhaenyra Targaryen, through her sons with Daemon Targaryen.
On the other hand, the Mad King's true name is Aerys II, and he arrives a few decades later in the Targaryen family tree. Aerys II and Aegon V are related, with Aerys being the grandson of Egg and his future wife, Betha Blackwood.
The fortune teller's prophecy does come true for Egg, as the young Targaryen goes on to become King of Westeros. He is known in Martin's writings as "Aegon the Unlikely" as he was the fourth son of a fourth son, and thus his chances of gaining the throne were slim. However, due to some abdications and the Council's involvement, Aegon V eventually becomes King.
Aegon V's reign is generally known as a fair one. Due to his time squiring for Ser Duncan, which is currently being explained in A Knight of the Seven Kingdoms, he passes many laws that benefit the smallfolk of Westeros. However, this was frowned upon by the wealthier houses and Lords of Westeros, which is why the fortune teller notes that many "rejoice" in his dying. Aegon V does eventually die in a tragic fire at Summerhall, but it's not related to wildfire.
Before his death, Aegon V sires several sons, thereby extending his lineage by a further generation to Aerys II, the son of Jaehaerys II. Aerys II eventually becomes the father of notable characters Rhaegar, Viserys, and Daenerys Targaryen, bringing the House of the Dragon, A Knight of the Seven Kingdoms, and Game of Thrones dynasties together.
While Egg's prophecy in A Knight of the Seven Kingdoms may make it seem like he's primed to be the Mad King, this isn't the case. The truth is that he is responsible for the future Aerys II, due to being his grandfather, but he doesn't go on to become the same Mad King from Game of Thrones lore.