There's two ways of looking at it. The Books are called "A Song of Ice and Fire". It's meant to symbolize the Starks and the Targaryens. I can just tell the way he's been building Jon Snow and Dany that they're meant to do something important. For one, they both started off hopeless. One, being pawned off to some warrior like a piece of meat......and the other, a bastard with no claim to anything. As you see with Dany, her story arc has went from that to now being a Queen in the making. Then with Jon Snow, he's the only main character to have ventured this far north into the Wilding camps. The story will end with those two. He wouldn't have spent so much time giving them such rich story arcs for them to be nobodies. He wouldn't have started the story focusing on the Stark family unless they're the central focus. If you've read ahead, you know Robb isn't the chosen one from the family, its Jon Snow. George R.R. Martin wants to tell the story of how a bastard boy climbs to power and how a weak & helpless girl becomes a powerful woman.


The other way of looking at it. I think this is the most likely one. Again, the Books are called "A Song of Ice and Fire". Lyanna Stark was kidnapped by Rhaegar Targaryen, who was the oldest son of the Mad King Aegon. The war started because of this, because Robert Baratheon was set to marry Lyanna. Rhaegar had married a woman from House Martell & had two kids with her. We know from the books/show, that Robert's army killed Rhaegar's two children to ensure the throne was his. Lyanna Stark was being protected by the kingsguard during the war. She was supposed to be a slave right? Why on Earth would the Kingsguard be protecting a slave, and not Rhaegar's wife and children? That doesn't happen. The Kingsguard protects the royal family only. Lyanna and Rhaegar fell in love.....atleast that what most fans of the book think.....he took her as a second wife and Lyanna Stark was pregnant with Jon Snow. That's why the Kingsguard was guarding her castle. That's why Lyanna's last words to Ned Stark was "Promise Me, Ned".....which was to take Jon Snow as his bastard, to never tell a word to Robert because Robert would've killed a Targaryen child. That's why Ned Stark tells Jon Snow in the beginning he may not have his name but, he has his blood. It's why Ned didn't elaborate further to Robert who Jon's mother was in Season One when they were talking about all the whores they fucked. Ned is the most honorable man in Westeros, why would he have an affair? Jon is his nephew. Not his son.

Prince Rhaegar Targaryen (Fire) falls in love with Lyanna Stark (Ice) and they have a child: Jon Snow. And a war was started because of it. A Song of Ice and Fire.