✖ : Describe a way to make them uneasy or apprehensive. 

JACK, when confronted by his own mortality tends to be at his most apprehensive. While this is true for most people with a sense of self preservation, it is exceptionally notable that Jack’s response to this feeling of impending doom known to all souls is not to take a deep breath and relax, but rather to go on a wild adventure in search of immortality, instead. Only to, one might add, sacrifice all possibility of immortality in order to save someone who won’t even thank him for the trouble.