This story contains spoilers from last night’s Game of Thrones episode, ‘Oathbreaker.’

For anyone who’s actually marathoned to read the A Song of Ice and Fire books, you know that Game of Thrones has mostly completely diverged away from the canon. From Jon Snow’s dramatic reanimation to Tyrion Lannister’s sudden stand-in as ruler of Meereen, show-runners David Benioff and Dan Weiss have really taken the reigns to lead Westeros in their own direction of choice. Last night’s episode was no exception.

While the third episode of the season, ‘Oathbreaker,’ was brimming with book-divergent moments, like Jon Snow cutting the ropes and letting his murderers, Allister Thorne, the fan-hated Olly, and others hang, no scene has been more talked about in the following hours than the ‘Tower of Joy’ scene.

It began with Bran Stark, standing in with the Three-Eyed Raven (Max von Sydow) before a dusty desert tower on the border–though this is never explicitly specified in the actual show–with Dorne. A man, revealed to be Ser Arthur Dayne aka the Sword of the Morning, leans against the wall polishing his sword as a small cavalry approaches him. One of the riders, Bran recognizes immediately, to be his father, Ned Stark, when he was younger. Young Ned demands that Ser Dayne reveal the contents of the tower behind him, specified in the books as the ‘Tower of Joy.’ Dayne, wearing the symbol of the newly-fallen Targaryens on his breastplate, refuses and a battle ensues, leading the slaughter of everyone except Ned and his bannerman Howland Reed. Ned would tell this story to his children, long before his death and Bran’s supernatural introduction to the moment, and would claim that he killed Dayne himself. As it turns out, Howland Reed stabs the knight in the back before Ned finishes him off. Then, someone screams from the tower, and the two survivors charge off towards it.

That scream is exactly what’s sent the book-reading Game of Thrones fandom into a frenzy. While the theory’s widespread at this point but never proven in the novel series, the fan-accepted “R+L=J” idea seemed to be hinted at heavily in last night’s episode. As the story goes, Lyanna Stark was kidnapped by the Crown Prince Rhaegar Targaryen during Robert’s Rebellion, which is canon–that’s been pretty explicitly stated in the books as well as the show. It’s also been said multiple times that Rhaegar raped Lyanna once he stole her and, as the books illustrated, locked her away in a tower–the presumptive same tower shown in last night’s episode. But then, the theory continues to guess this: Lyanna became pregnant by Rhaegar and had a kid before she died–in a “bed of blood,” as the books say–and Ned’s oath to her was to raise her baby as his own–and that baby is Jon Snow.

And if Jon is actually Lyanna and Rhaegar’s child, that would actually make him another living Targaryen, and possibly the rider of the third dragon. And it seems that the first tangible hint of that happening in the HBO world was just there for the taking in ‘Oathbreaker.’

Of course, there’s still a whole season–and two more after this–to go, and as fans discovered last night, the Benioff and Weiss duo aren’t planning on revealing their crown plotline just yet, to fans’ distress.

HBO just poured ice in the entire fan base with that Tower of Joy scene. Got my heart rate up. #GameofThrones pic.twitter.com/VfPIL0zTs8

— This is redundant. (@Burrrittanie) May 9, 2016

@MNovak88, I have no idea who you are but this encapsulates all of my feels right now

— Herman Johannesmeyer (@hermcakes) May 9, 2016

Fans have waited this long to find out if Jon Snow is really a Targaryen, though; they’ll only have to wait two years more, at most.