In short, at least in older versions of the setting, when changelings reach a certain point - age often helps - of banality in their lives, they fall into a stage where they forget their fae souls. But their human bodies live on...
The temperatures were over 100F. There was a drought on that had been going for more than a month. The city had been in and out of water restrictions since late May, and the sun was searing down as if it was trying to bake everyone who dared to go outside.
And on a street in a neighborhood where the police always went in twos and preferably in threes, a hydrant was spraying water all over the sidewalk and the road.
Seven children from toddler age to teens were dancing in the water. Normally, the police would chase them off, close the hydrant, and maybe make stern noises at the oldest of them. But this time, they were dancing with two grey-haired people who were definitely old enough to arrest.
Hell, their retirements might be old enough to arrest.