Originally starting off as a nickname Sarah gave Renn, "Rennifly" has also come to mean a type of endangered butterfly found only on the Sueniverse.

Follow the Renniflys! Follow the Renniflys!

Renniflys are hunted by gloomops, and therefore must constantly be hiding. Megan is convinced that Renniflys are made of frostings, and would therefore make a good pie.

As of late, Rennifly has also come to be the nickname of Renn's self-insert, given to her by the Máté Kamarás version of Der Tod.