Demons

When I started work, it was common for people to smoke in the shared offices.

After a while, the smokers were banished to "smoking rooms" which were smelly, stained rooms with a few chairs and a coffee table containing several copies of Woman's Weekly.

Later, the smokers were given little see-through bus shelters outside.

Now, they can only smoke in small designated areas that are exposed to the wind and the rain. And they have to stay within the green-painted borders that mark the limits of the "smoking areas".

Like Demons who, once summoned, must stay within the pentagram drawn by their summoners.