"When I was 9, we were buddies forever -- 'blood brothers.' We pricked our fingers, mixed them and sucked them," Stern said. "In that sense, it's a way of binding a community beyond the usual forms of understanding. On a rational basis, you can say 'what the hell are they doing?' But on an instinctive basis, then we're bound much more."
Giving another person a hicky could also be considered a mild form of vampirism. "Bringing blood to the surface [means] you're bound to me by this blood sign," he said.
Although the desire to "possess" a person by drawing their blood can indicate insecurity, he said, the sign of blood means protection, too.
Vampirism certainly comes with extremes, Stern cautioned. But given the elements of vampirelike rituals embraced by cultures all over the world, he said, somewhat tongue-in-cheek, "it's hard to separate out 'vampire.' It sounds great on Halloween, [but] everybody's slightly a vampire."