'Game of Thrones': A Closer Look at the Most Important Scene in the Season Six Trailer

Why "He dreamt an old dream, of three knights in white cloaks, and a tower long fallen, and Lyanna in her bed of blood" is a big deal for the HBO series.

"He dreamt an old dream, of three knights in white cloaks, and a tower long fallen, and Lyanna in her bed of blood." So begins chapter 39 of A Game of Thrones, the first book in George R.R. Martin's A Song of Ice and Fire saga, and the basis for the hit HBO show. The sentence makes little sense to the casual Thrones viewer, but for many fans, it means everything — and soon, it'll matter to everyone.

HBO's first full trailer for season six comes packed with material, much of it of the blink-and-you'll-miss-it variety. The most important of these quick cuts involves a character not featured on Thrones since the very first season: a young Eddard Stark, the original protagonist of the subversive fantasy series, battling against three knights wearing Targaryen armor. 

Ned lost his head long ago, but the Warden of the North's work on the show will resume in the coming season, according to the trailer … and he just might come equipped with the single most important reveal in the series thus far.

Let's rewind to the initial quote. It comes at the midpoint of A Game of Thrones, shortly after Ned suffers brutal injuries in his King's Landing quarrel against Jaime Lannister. Ned experiences something between a fever dream and a vivid memory, recalling the days of Robert's Rebellion, the war that all but demolished House Targaryen, and put the Baratheons (and, subsequently, the Lannisters) on the Iron Throne.

In the final days of the war, Ned and six allies traveled to the Tower of Joy, a Dornish stronghold where Prince Rhaegar Targaryen was holding Ned's sister Lyanna hostage — or so the story goes. Three of the finest warriors in Westeros, including the legendary Ser Arthur Dayne, were charged with guarding Lyanna, living and dying by that sworn duty in battle against Ned's group of warriors. Eddard won the fight, but emerged as the sole survivor, save for his ally Howland Reed, an enigmatic figure at the heart of infinite Game of Thrones conspiracy theories. (He's a story for another day.)

Ned relives this battle as a bedridden nightmare, complete with the cruel ending: Lyanna, after everything, died at the Tower of Joy, inside "a room that smelled of blood and roses," consumed with a fever. Before she passed, she spoke three dying words: "Promise me, Ned."

The Tower of Joy, Lyanna's death, and her three final words have been painstakingly analyzed since A Game of Thrones first came out in 1996. As the story progressed over subsequent years and books, enough textual evidence mounted until virtually all readers agreed: Lyanna died during childbirth, bringing none other than Jon Snow into the world — the son of Lyanna and Rhaegar, with the ice of House Stark and the fire of House Targaryen flowing through his veins. 

If true, the theory explains why Ned would go to such great lengths to keep his "bastard" son's heritage a secret; if noted Targaryen haters like King Robert were to learn about Jon's actual father, then Lyanna Stark's secret son would not be long for this world.

The theory behind Jon's parentage is commonly referred to as an equation: R+L=J. But cold mathematics betray the nuclear story potential of such a twist. If Jon's not the son of Ned and some unnamed woman, but instead the son of Lyanna and a Targaryen, then he boasts a legitimate claim to the Iron Throne.

Well, he would have a claim to the Throne — if not for the fact that he's presently dead. 

But this is exactly why so many fans are thoroughly energized by the sight of the Tower of Joy sequence in the season six trailer. At the very least, it's a callback to one of the most legendary moments in the history of the Starks and Targaryens, a scene that was far from guaranteed to making it onto the show. At the best, it could confirm the longstanding theory that Jon Snow is the song of ice and fire at the heart of this tale, and the hero destined to one day rule Westeros. It's just one of many reasons why fans are so adamant that the 998th Lord Commander of the Night's Watch will return from the grave; he, like Ned, has a promise to keep.

Rewatch the season six trailer:

Game of Thrones returns on April 24.