The story of the Knight of the Laughing Tree is one familiar to A Song of Ice and Fire readers, but completely unknown to those who have only watched Game of Thrones. At first glance, the tale might seem like one of the dozens that George R. R. Martin peppers his larger narrative with. It's undoubtedly part of his masterful world-building, but it might actually provide the backstory for some of the most significant events in Westerosi history. Why is the Knight of the Laughing Tree so important? Two words: Lyanna Stark.
As the impetus for Robert’s Rebellion and the mother of Jon Snow, Lyanna Stark is incredibly important to the overall narrative of A Song of Ice and Fire. Because of the central mysteries tied into her character, much of her personal backstory has been intentionally obscured by George R. R. Martin. However, ever the sneaky author, GRRM may have left some of the most important parts of Lyanna’s story hiding in plain sight, through the tale of the Knight of the Laughing Tree.
In 281 AC (281 years after the events of Aegon’s Conquest), a great tournament was held at Harrenhal. All of the great houses had representatives at the tourney, including some of A Song of Ice and Fire’s most significant figures, like Ned Stark, Robert Baratheon, Rhaegar Targaryen, and (somewhat surprisingly) Mad King Aerys II Targaryen. Alongside these important characters were some of Westeros’s all-time greatest fighters, including Barristan Selmy, Arthur Dayne, Jaime Lannister, and Oberyn Martell.
Despite the heavy competition, Prince Rhaegar won the day, out-jousting all of his opponents. As champion, Rhaegar was given the opportunity to name someone the Queen of Love and Beauty, and he caused great scandal by bestowing the honor upon Lyanna Stark instead of his own wife, Elia Martell.
Many believe the seeds of Robert’s Rebellion were sown in this very moment, making the Tourney at Harrenhal one of the most significant events in Westerosi history. It also happens to be the scene of a whimsical side story from the books about the Knight of the Laughing Tree, but the two events might be more closely related than it initially appears.
Although the reader gets snippets of the story of the Tourney at Harrenhal throughout A Song of Ice and Fire, the tale of the Knight of the Laughing Tree is told by Meera Reed to Bran Stark, with assistance from her brother, Jojen. The story’s main characters are only described by nicknames like “the Young Wolf,” but it's abundantly clear Meera is talking about her father, Howland Reed, and the four Stark siblings — Brandon, Ned, Lyanna, and Benjen.
In the story, young Howland is bullied and attacked by three squires, only for Lyanna Stark to show up with a blunted sword and beat the squires away, saving her father’s bannerman. Howland is invited to attend the night’s feast with the Starks, where he and Lyanna identify the attackers and the houses they represent. Benjen offers to find Howland armor and a horse so he can avenge himself, but Howland appears unwilling.
The next day, a mystery knight shows up at the tourney, described as being "short in stature and wearing mismatched armor." The knight carries a shield decorated with a chuckling weirwood tree — hence the Knight of the Laughing Tree. Clearly motivated by the previous days events, the Knight of the Laughing Tree challenged and made quick work of the three knights whose squires had bullied Howland.
When those knights attempted to ransom their armor and horses back, the mystery knight announced that teaching their squires some respect would be payment enough, and then promptly disappeared, never to be seen again.
Upon hearing the story, Bran Stark instantly declares the crannogman in the story, Howland Reed, must be the mystery knight. In the world of A Song of Ice and Fire, when a character is this certain about something, it's usually a clue they’re dead wrong. It doesn’t really fit with Meera's character to tell a story that only serves to brag about her father being a badass, nor is martial prowess something much associated with Howland Reed. Furthermore, there are strong hints the tale has significance to the Starks.
Throughout Meera telling the story, Jojen continually expresses his astonishment that Bran hadn’t heard it before. He states that he thought Bran would have been told this “a hundred times” by his father. This shows that, in the opinion of the Reeds, the story is important enough to the Starks that everyone in the family should know it. But why?
The Knight of the Laughing Tree is, beyond a shadow of a doubt, Lyanna Stark. Although there have been other theories about the knight’s identity, from Howland himself to Ned or Benjen Stark, there is too much evidence implicating Lyanna to ignore.
Lyanna certainly had the motivation. She was the one who originally rescued Howland, and the one who showed the most indignation at her fellow Northerner being abused. She also had the jousting ability; she's described as one of the finest riders in the Seven Kingdoms and “half a horse.” Lyanna was also known to practice fighting in secrecy with Benjen, thanks to Bran’s tree-visions, which show she had martial prowess. She just didn't have the freedom to express it publicly.
The Knight of the Laughing Tree’s mismatched armor suggests an individual who didn’t have their own set, and that would have been true for Lyanna. The short stature of the mystery knight definitely matches hers, and the reported “booming” voice could have been a result of her armor echoing.