Warning! SPOILERS ahead for Game of Thrones season 8 premiere.
During the Game of Thrones season 8 premiere, Jon Snow mounted and rode one of Daenerys' dragons, fulfilling not only the wish of fans the world over but potentially an important prophecy as well. But how is it Jon can so easily ride a dragon?
Ever since their introduction in the Game of Thrones' season 1 finale, the dragons have become one of the most popular aspects of the series, often featuring heavily in HBO's marketing. Within the show's narrative, the dragons serve as symbols of Daenerys' Targaryen heritage, reminders that her claim to the Iron Throne is backed up by some serious firepower. And yet, that power took a hit in season 7 when the Night King successfully kills and later turns one of her dragons, Viserion, to his side. Now down to only two dragons, Daenerys will need to tread carefully is she's to keep her remaining children alive - and that may mean trusting someone other than herself to ride them.
In the Game of Thrones season 8 premiere, that's exactly what happens. After noticing how intrigued her dragons are by Jon, Daenerys suggests he try riding one. Jon is understandably nervous, saying he doesn't know how to ride a dragon. Daenerys responds that no one knows how to ride a dragon until they do it, at which point Rhaegal leans down, inviting Jon to climb aboard. With Jon hanging on for dear life, Rhaegal takes to the sky, and just like that, Jon becomes a dragonrider. But how come Jon is able to ride a dragon so easily? The answer most likely lies in his Targaryen blood.
Before The Doom destroyed Valyria, all of the dragonlord families would regularly ride their dragons. Anyone at any age could become a dragonrider, but it was essential that they bond with their dragon before attempting to ride them. Once that bond is formed, however, a dragon will never allow another person to mount them as long as their rider lives (the only exception being if another person rides with that dragon's rider, as when Daenerys rescues the group in season 7's "Beyond The Wall"). Dragons live much longer than humans, so they may have several riders in their lifetime, but they will only ever bond with a person who has the blood of old Valyria.
The Targaryens are the only surviving dragonlord family, having escaped to Dragonstone before The Doom. They continued the dragonriding tradition, using them to conquer the Seven Kingdoms. Eventually, though, their dragons died off, and no more dragons meant no more dragonriders. Then Daenerys "birthed" three dragons from petrified eggs, returning dragons to the world for the first time in a century. As their mother, Daenerys is close with all her children, but it is with Drogon whom she shares a special bond, riding him as her mount and becoming the first Targaryen dragonrider in generations.
Like Daenerys, Jon is also a Targaryen and therefor has the blood of old Valyria running through his veins. It's why Drogon allowed Jon to calmly stroke his face in season 7, and it's why Rhaegal lets Jon climb on his back in the season 8 premiere. Exactly why it is that only those who are descended from Valyria can ride dragons is unknown, but with Jon being only the second person on Game of Thrones to ride a dragon, that connection seems to be confirmed. Presumably, Rhaegal and Jon are now bonded for life, and as long as Jon lives, Rhaegal will accept no other rider but him.
Jon riding Rhaegal doesn't just grant fans their wish of seeing him ride a dragon (and the one named for his father, no less), it also potentially fulfills the dragon has three heads prophecy. The phrase is first heard when, in the novels, Daenerys is in the House of the Undying and has a vision of her brother, Rhaegar, telling her that the dragon must have three heads. This motif is also seen in the Targaryen sigil of a three-headed dragon as well as in the three dragons who Aegon and his sisters rode when they conquered Westeros. Many have since assumed that the prophecy means Daenerys' three dragons will have three riders and it appears that prophecy has since come to pass.
However, fan speculation had always suggested the three riders would be some combination of Daenerys, Jon, and either Tyrion or Bran, given the theories that Tyrion himself might be a Targaryen and Bran's ability to warg. Instead, though, the three dragonriders on Game of Thrones are Danerys atop Drogon, Jon with Rhaegal, and the Night King's abduction of Viserion. Could this mean the Night King is also a Targaryen? Possibly, though it's just as likely that whatever magics are in play when the Night King resurrects the dragon may supersede any Valryian-dragon connection. Still, there are now three dragonriders, so the dragon does have three heads, and it may just mean that two of those heads need to devour the other in order for the Great War to end.
Game of Thrones season 8 continues Sunday, April 21 at 9:00 pm on HBO.