Jon Snow is the bastard child of Eddard Stark. Jon, like his Uncle and many Starks before him, joins the Night's Watch with his trust albino dire wolf, Ghost, at his side.
Tyrion: Let me give you some advice bastard. Never forget what you are. The rest of the world will not. Wear it like armor, and it can never be used to hurt you.
Jon: What the hell do you know about being a bastard?
Tyrion: All dwarfs are bastards in their father's eyes.
The White Walkers don't care if a man's free folk or crow. We're all the same to them, meat for their army. But together we can beat them.Jon