As a child not understanding the scope of what had happened, you tried to find it at that time but the carnival owners - a pair of elves named Mister Witch and Mister Light - were decidedly unhelpful.
"Silly little screeching cricket," said Witch. "You forgot to buy a ticket."
"The Carnival goes round and round," said Light. "The multiverse is our playground. Nothing's free and nothing's lost. Every visit has a cost."
---
As time passed, your heart became less heavy, and you gave less and less thought to those childhood events. You learned to live with the loss, but have been forever lessened by it. Some went back to their normal lives, while some even traveled with the Carnival hoping to fill that void, but neither has found what was lost. Now, for reasons you can't explain, the longing to retrieve that which you have lost has resurfaced, as though an old spell has faded away, allowing you to feel the loss as sharply as if it happened yesterday.
The Witchlight Carnival has returned exactly on the eighth year, and you find yourself standing near a ticket booth by the entrance at twilight, just as the Carnival is about to open. There you meet others who look as troubled as you, dressed as both attendees and Carnies. Without knowing how or why, you sense that each of them has lost something as well. Perhaps fate has brought you together.