There is a lot of mystery surrounding the foggy cities as is, first their sudden misty appearance out of nowhere brought panic and confusion, been stared at by many days before a force task was ensured into braving in, only to get lost on its protective magic the first few tries, deemed to want harm against its city and thus thrown back the way they came.
Only when a brave researcher, bounded by no more than his interest and curiosity, managed to enter and leave to tell the tale.
Afterwards he ended up being sent as a massager many times to come, taking so long to establish a way of steady communication that it gave enough time for the vampires and werewolves to be digested by the population in general as the new knowledge of the supernatural settled down enough that the creatures of the dark could come out of their city to make treaties with the humans about safety measures and friendliness.