Anxiety and the Chills - The Cause and Connection. The idea is that the anxiety of the horror movie provides a level of fear that sends chills down your spine. Anxiety has often had a connection to chills, even though the exact relationship between anxiety and these chills often seems so unclear.
No one knows for sure. The popular theory is that the Night's King is indeed a Stark. That he was the Lord Commander of the Night's Watch who lived during the Age of Heroes, 8000 years before the time of the series. It's believed he fell in love with a female White Walker, fell in love with her and that they mated.
If the Night King has any inkling that Bran is the reason for the Wall, the Night King has very good reason to want Bran dead. If Bran dies before he goes back in time to have the Wall built, then the Wall will cease to exist giving the Night King free access to the humans, which is what he has wanted all along. Or maybe it's not that complicated, and perhaps the Night King just likes killing people and Bran's an easy target.