We all have that fear.
The fear that we have some random creeper following us around who mysteriously knows everything about us. The one whom you've never met in your life who, right after introducing themselves, proceeds to ask you why you like to have a hot pumpkin spice latte right after your Zumba class (seriously, a hot, rich, sweet drink like that after physical exercise? Ick!).
Jack Vale exploits that very fear, introducing himself to total strangers while knowing just a bit too much about them to be normal...
... okay, way too much, not just a bit.