One distinctive feature of Fairy is the flow of time; in most cases time in Fairy seems to move at a different pace than on Earth. We may see a single night go by in Fairy while years pass on Earth, or in one anecdote years passed for a man in Fairy while only minutes passed here. We see a variety of stories where a person joins a fairy dance for what they believe is only a single night only to find at dawn that years, decades, or even a century has passed while they danced.
In the tale of King Herla a single night of feasting in Fairy occurs while 200 years pass on mortal Earth. There is no clear predictable pattern to this, however, and the fairies themselves seem exempt from the disjointed temporal effect, as they often and regularly cross between the two worlds, even maintaining friendships with mortals over the length of the person’s lifetime, without difficulty. The same is obviously not true for mortals, or at least not without fairy aid, as we see many mortals doomed by their time in Fairy because they return to a world that is utterly changed from the one they left by nothing more esoteric than the passage of time.