37. Stockholm Syndrome
This situation is a bit out there but you’ll see what we mean by it. For those unaware, a person with Stockholm Syndrome happens to be a person that is captured or taken from their families and former life. They may end up being held by their captures for a while and the syndrome may begin to kick in where they start to have a psychological alliance with them.

Essentially, they’ll see them as family members and begin to care for them. If by chance this family was one that got off on cannibalism or acting like the undead to capture other people, the person with the syndrome may end up helping and/or taking part. Now, they’re part of it all. Imagine if this was done in a mass effort across the world. Starting to see how it could become something of a real zombie apocalypse yet?