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.
Mance: When we first met you were my prisoner and now for our last meeting...
John: This doesn't have to be our last meeting.
Mance: No, but it will be.
John: You know what Stannis wants?
Mance: He wants me to bend the knee and he wants the free folk to fight for him. I'll give him this much, he's bold.
John: Shouldn't a king be bold?
Mance: Oh I respect him. If he gets what he wants I expect he'll be a better ruler than the fools sitting on the Iron Throne the last two hundred years... but I'll never serve him.