The “monster response” in fluffies is thought to be a half-finished copy protection mechanism meant to defend against fluffy bootlegging attempts. The fear of alicorns is the most well-known, but fluffies that haven’t been properly socialized also fear disfigured fluffies, genetically engineered fluffy subspecies, fluffies with excessively colorful body patterns, other biotoys with equine or fluffy-like features, horses (and other ungulates), and any animal from the size of a mouse to the size of an adult fluffy with the exception of cats and dogs.
The jellenheimer is an early attempt at modifying the fluffy genome. It’s just a little guy.