Game Of Thrones: 12 Easter Eggs You Probably Missed In Season 5
8. "You Know Nothing, Jon Snow"
The moment Melisandre attempted to seduce Jon Snow - perhaps aware of the power of his blood (?) - was a skin-crawlingly uncomfortable one for the Stark bastard and the audience. Not least because the Red Witch is one of the most disquietingly charismatic characters in the show, and her power is the kind that corrupts absolutely. Or just straight up kills people.
But in that moment, the witch offered a fan-baiting moment, casually requoting Ygritte as a means to stab at him for shunning her advances. That wasn't the end of the importance of the exchange though, as it foreshadowed what was going to happen to Jon at the end of the season.
The quote carries more pertinence when you consider that both users of those fateful words have encountered Jon just before someone put something pointy into him, marking a huge betrayal of an almost familial relationship. At this stage, "you know nothing" might as well mean "you are literally about to suffer attempted murder."