Butterflies

When a sapient being has unstuck themself in time and is about to change an event in the past that is not meant to be changed, they are assaulted by a kaleidoscope of supernatural butterflies.

Sent by The River Without End as a last-ditch effort to avoid a Calamity and the subsequent reboot of the universe, the butterflies are only visible to the being who is about to end the world.

What follows is an example of the phenomenon taken from the novel The Dance of Dreams:

Matt gave Albert a nod and started again toward the couch where his parents-to-be were getting cozier and cozier with each other. But just as he was passing the TV, that old wooden thing he remembered from Grammy Carlene’s house that was probably brand new right now—just as he got within spitting distance of disrupting the past—he was surrounded by a whirlwind of butterflies.

 

It was the strangest damn thing. No one else seemed to see them, no one seemed to take note of anything amiss until Matt yelped in fright and took a step backward to get away from the maelstrom of many-colored wings. And even then, they got back to their drinks and their conversations quick enough—so quick Matt realized this couldn't have been the first freakout they'd seen that night, and that it probably wouldn't be the last.

 

He made his way back toward Belinda, only daring to ask “What the hell was that?!” once he could whisper it into her ear. 

 

“The Butterfly Effect,” she said, smiling. “Never let it be said that God doesn't have a sense of humor.”