Vampy Cats were misogynist madcap demon-followers of Twilight from the canonical comic series Buffy Series Eight, being the prominent villains in "Swell".
They took the form of catlike plush dolls in the fashion of Hello Kitty, only warped by dark magic into being violent little furballs intent on destruction and mayhem - despite this they were extremely popular playthings and were likely a homage to the Smile Time Puppets from Angel.
History[]
Vampy Cats were demonic plush dools designed to take advantage of the popularity of vampires in the media via mixing vampiric traits with that of another popular figure in media, namely stuffed animals - the result were relatively harmless looking creatures that were in reality little bundles of hatred wrapped inside a fluffy body.
the Vampycats merge to create the Swell
Vampy Cats could possess humans via a rather disturbing method of oral entry - which allowed them to control their victims - a Vampy Cat could be ejected from a host body if they were vomitted out (again, a rather disturbing trait but one that was rather successful).
Vampy Cats could also merge together to form a gigantic monster known as the Swell and indeed took this form to battle the Slayers known as Satsu and Kennedy in Tokyo, which was really part of Twilight's masterplan.
Harmony used the aftermath of this battle as an example of unprovoked aggression towards anything vampiric by Slayers (an obvious act of manipulation as the act was far from unprovoked).