Throughout history children have gone missing and never returned yet some of them are still alive just unseen by unknown forces. The snatchers have been talking children since the beginning of time but can only be seen the the decades chosen victim. Each victim has contributing features such as they were raised in a country they were not born in, they have limited contact with the outside world and most importantly they irrationally fear everything to exist and to not exist.
The fear is what attracts the creatures for these creatures are fear.