Game of Throne fans be aware: there are SPOILERS for the sixth season finale and anyone who has not read the books. And before you storm the Twitter or Facebook battlements to tell us we're wrong, it is still in the realms of speculation.
The Basics: who are Jon's parents?
R+L=J. For a long time now, this seemingly simple equation has been at the core of a big Game Of Thrones fan theory, years before the show aired. To open it out: Rhaegar plus Lyanna equals Jon, the idea that despite what Ned Stark (Sean Bean) has claimed in the past, Snow (Kit Harington) is actually the product of a union between Rhaegar Targaryen (unseen in the show thus far, and likely to stay that way unless Bran Stark ventures further back in time) and Lyanna Stark (Aisling Franciosi).
Now, while the vision in the Season Six finale (read our review of The Winds Of Winter here) didn't specifically confirm that Rhaegar is Jon's father, we do at least now know that Lyanna's Ned's sister is his mother. So how did it get to this point?
The History: how did this all happen?
Come with us on a journey through time and space to... Look, we're not the bloomin' Three-Eyed Raven, so let's cut the dramatics and get to what happened. Lyanna Stark, the only daughter of Lord Rickard Stark, head of House Stark and Lord Paramount of the North, is betrothed to Robert Baratheon as part of a political arrangement. At some point after the betrothal, Prince Rhaegar Targaryen won a tournament attended by Lyanna, rode past his wife, Princess Elia Martell, and placed a crown of winter roses, the crown of the Queen of Love and Beauty, on Lyanna's lap. Crowd: "Aaawww!" Robert: "WTF! That's my betrothed! And you're married!" Crowd: "Aaaaawakwaard..."
Lyanna was later abducted by Rhaegar, who took her south and hid her away in Dorne in a place known as the Tower Of Joy. You might recognise it from Bran's visions. Her brother Brandon Stark rode to King's Landing to demand Rhaegar's arrest and punishment. King Aerys II Targaryen had him and all his companions charged with treason. He demanded all their fathers, including Rickard, come to King's Landing and promised they would receive a fair trial. Instead the King had them all burned alive, which sparked the uprising known as Robert's Rebellion. The war almost completely destroyed House Targaryen, and Robert was installed as king after he personally slew Rhaegar at the Battle of the Trident.
During the conflict, Ned travelled to rescue his sister from the tower, only to discover that she was dying due to complications from childbirth, due to giving birth to her son, the father of the child heavily implied to be Rhaegar. Before her death, Lyanna asked Ned to promise in keeping her son and his heritage safe from Robert, who would have the child killed if he finds out. Ned complies with Lyanna's wish and takes the infant to Winterfell. Fulfilling his promise, Ned claimed the boy as his bastard son, and named him Jon Snow.
The Future: is Jon destined for greater things yet?
Jon, of course, has no idea about his true parentage for now: only Bran (Isaac Hempstead Wright) has seen the truth and everyone else who knows is either long dead or not in a position to say. What does it mean for our moody hero, freshly anointed as the latest King In The North? For now, not that much, though it'll be interesting to see what happens next season when Daenerys Targaryen (Emilia Clarke) arrives in Westeros. If Rhaegar truly is Jon's father (as the show appears to be pointing towards), then that makes Daenerys his aunt (complicated family dynamics? On Game Of Thrones? Surely not!) That could well come into play if they meet in battle, potentially deciding whether Dany decides to turn him into melted Snow or – squick alert – sees him as a potential husband in her quest to rule Westeros. Look, it's not like that sort of thing doesn't happen there. Quiet, you.
But lest it start setting up yet more weird dynamics, no one knows what will happen when Jon and Dany actually meet, assuming they even do. And when Jon eventually learns the truth, which you have to figure the writers are holding on to for a big revelation down the road. Beyond all that, Jon could conceivably have some of the powers that Dany displays, or an entirely different set depending on what his Stark blood does to his system. We know he can't cheat death except with a little magical assistance, but his presumed Targaryen side could help him if Drogon and co. come a-roaring. And what of his claim to the Iron Throne? He might not be Ned Stark's son, but thanks to Lyanna, he has his blood coursing through his veins, meaning some actual connection to the lineage, despite his continued status as a bastard.
So while we haven't 100% finally had Jon's parentage confirmed, let's consider it all but sealed. On to people still hoping that Lady Stoneheart will show up for some zombie vengeance!
Season 6 - Episode review guide