(Editor's note: Major Game of Thrones season six spoilers ahead.)
Jon Snow (Kit Harington) is officially alive and kicking (or gasping for air, really, based on the last episode), and worried fans have finally been assured that the character wasn't actually killed off. While there are many questions lingering about the road ahead for Snow — chief among them is how he will react to his Night's Watch brothers assassinating him — the show is also preparing to reveal a long-debated theory: Snow's true parentage.
On Sunday, HBO released a preview for the season's third episode, and one of the scenes teased points to an integral moment from the past. With Bran Stark (Isaac Hempstead-Wright) entering another flashback with the help of the Three-Eyed Raven (Max vox Sydow), it seems we're given a glimpse of the aptly named Tower of Joy — a location mentioned in the books that hosted a bloody confrontation about 15 years before the events of season one.
A Song of Ice and Fire readers know of the Tower of Joy from a notable flashback sequence related to Ned Stark. The pivotal moment takes place after the events of Robert Baratheon's Rebellion against the "Mad King" Aerys II Targaryen, leaving Aerys and his son, Prince Rhaegar Targaryen, dead, along with nearly the entire family's lineage. At that time, three of Aerys' Kingsguard — still loyal to the Targaryens — were standing guard at the Tower of Joy.
Inside is where Lyanna Stark, Ned's sister, is being kept (after either being kidnapped by or having run away with Prince Rhaegar). When Ned Stark and his company arrive to retrieve Lyanna, a brutal battle ensues between the fighters gathered, as hinted in the preview with a young Ned and Ser Arthur Dayne (of note: the dialogue between the two is transferred word-for-word from the books).
Obviously Ned survives, as he's the initial protagonist of the series, and finds Lyanna inside the tower in a "bed of blood." And here's where the "R+L=J" theory enters. It stipulates that the "bed of blood" is, in fact, a complication of childbirth — with the child being Jon Snow, and the father being Rhaegar.
Moreover, Lyanna's final words to her brother are "Promise me, Ned," which has been interpreted as a pledge to keep this child a secret, as the new king Robert wouldn't allow a child that is half-Targaryen to live. Not only would this theory answer the question of Jon's parentage, but it would mean the character is even more important than we perceived. As a half-Stark, half-Targaryen, not only would Jon Snow have a legitimate claim to the Iron Throne, he could also be interpreted as George R.R. Martin's A Song of Ice and Fire personified.
While it's still just a theory, all signs point toward a stunning reveal in the third episode. Perhaps Jon will finally learn the identity of his mother, which Ned promised to reveal the next time they saw each other — before he was executed.
YouTuber Alt Shift X put together a more comprehensive explanation of "R+L=J," which you can check out below.