The Big 'Game of Thrones' R+L=J Theory, 100% Explained

game of thrones birth of baby
This post contains major spoilers for all seasons of Game of Thrones.

If you're a Game of Thrones fan, chances are you've stumbled upon the "R+L=J" theory at some point in your internet perusing. Since the publication of George R. R. Martin's first book in 1996, "R+L=J" has been a popular belief held by fans, and according to Know Your Meme, has been known by its formula shorthand since at least 2006.

And now, as we learned in the Season 7 finale "The Dragon and the Wolf," this fan-parsed history lesson is canon. In the finale, Bran explained to an eager Sam that there was more to Jon's heritage than being the bastard son of Ned Stark. In fact, he's the Aegon Targaryen, son of Rhaegar Targaryen, and basically the heir to the Iron Throne. Seriously.

OK, OK, OK, that's a lot to take in. What, exactly, does it mean? For the uninitiated -- or the foggy-brained -- here's a primer on the elusive letters: what they stand for, who they affect, and what they mean for the future of the series.

game of thrones birth jon snow

Who is Jon Snow's mother?
This is the question every fan wonders when they're first indoctrinated into the series, whether by show or book. Jon Snow, grows up believing he's the bastard son of Ned Stark. But he's never told who his mother is – not by Ned, not by anyone. We know she must be someone special, as Ned was betrothed to Catelyn when Jon was born. What sort of woman could sway him -- a man so pledged to honor that he's literally executed for it -- from his sworn duty? Even Ned's best friend, King Robert Baratheon, is denied the details of her identity.

But book readers long-ago decoded certain textual clues to suggest that Jon's mother is actually Lyanna Stark, Ned's sister, and that Ned isn't actually the father. The inference is something the show confirmed in the season 6 finale, during one of Bran's Weirwood visions. In the books, Ned discovers Lyanna in the Tower of Joy, drenched in blood. Her final words ("Promise me, Ned") haunt and taunt him, a reminder of the lie he etched in stone, and ultimately carries with him to the grave.

So, that's the "L" part of the equation, and the "J" is there for Jon. But who is the "R"?

tower of joy

Who is Jon Snow's father?
Robert's Rebellion was a civil war that erupted in Westeros after Lyanna was kidnapped by Prince Rhaegar Targaryen, son of the Mad King Aerys and brother of Daenerys. Lyanna was betrothed to Robert Baratheon, and her "capture" set him off. Many battles were fought, but Robert eventually killed Rhaegar, Jaime Lannister killed the Mad King, and Robert claimed the throne. Ned found Lyanna shortly after Rhaegar's death, and took baby Jon back to Winterfell, where he raised him as his bastard son.

The show cuts to whisper when Lyanna starts talking specifics, so viewers, who share Bran's point-of-view of the moment, still aren't sure who the father is -- but all signs point to Rhaegar. They were together for more than a year by the time Jon was born, and there are no other likely candidates. This would also explain why Ned would raise Jon as his own – to protect him from the Targaryen-hating Robert. Lyanna's final words – "promise me, Ned" – were a plea to keep Jon safe from Robert's wrath.

Were Lyanna and Rhaegar in love?
The general consensus is that Rhaegar captured Lyanna after growing infatuated with her at the Tourney of Harrenhaal, a celebratory festival that brought together many noble families from across the Seven Kingdoms. Rhaegar was married to Elia Martell -- sister of Oberyn -- at the time, and had two children, Rhaenys and Aegon, but this didn't stop his pursuit.

But while the Rhaegar-Lyanna relationship looked like an abduction, there's reason to believe that she went with him willingly, and that they were deeply in love. For starters, Rhaegar was admired by those in his orbit, including Barristan Selmy, who served the Targaryens. "Rhaegar never liked killing – he loved singing," Selmy tells Daenerys of her brother. Rhaegar's gentle nature is relayed by many, and in the books even Ned doesn't think of him as dangerous. There's even more evidence if you go looking, but long story short, it's pretty likely that Rhaegar and Lyanna's love was mutual.

Were Lyanna and Rhaegar married?
Unclear. The Targaryens were known to practice polygamy, and some fans even speculate that Rhaegar was able to annul his marriage to Elia and secretly wed Lyanna. There's no proof of any of this, but it does seem likely, if only to legitimize Jon's birth.

But that means…
Yup. Rhaegar's eldest children were murdered in Robert's Rebellion, so if Lyanna and Rhaegar were indeed married, that makes Jon Snow the rightful heir to the Iron Throne – above Daenerys, who would be his aunt.

This is a big deal. Not only does it complicate Dany's conquest of Westeros, but it also lends a poignancy to Jon's resurrection, making it more of a rebirth – Jon Snow is dead, but Jon Targaryen lives. Martin's series is called A Song of Ice and Fire, and if Jon is half Stark (ice) and half Targaryen (fire), it's likely that he's the ultimate hero of the story – the one who will unite the kingdoms, either by serving as king or by destroying the White Walkers. Perhaps he'll even ride a dragon.

john snow

Will Jon ever learn of his parentage?
It's hard to say, but probably. Bran knows one half of the equation, and there's much speculation that Samwell Tarly, who's currently at the Citadel, might stumble upon some revealing document in his research. It's also possible that Petyr Baelish is in on the secret, considering the knowing glance he tosses at Sansa in the Winterfell crypts when they discuss Lyanna. Might he use that to further drive a wedge between Sansa and the new King in the North?

We'll have to wait and see if season 7 finally, at long last, confirms the R+L=J theory. Watch and see when Game of Thrones returns to HBO this Sunday, July 13.

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Lindsey Romain is a writer and editor living in Chicago. She covers politics for Teen Vogue and has also appeared in Vulture, Birth.Movies.Death, and more. Follow her on Twitter @lindseyromain.