The Black Moon sisters are some 
of the less important badguys in R. There are four of them: Catsy, Birdy, Avery and Prisma. In the anime they are fashion obessesed ditzs who have powers, which are the exact reciprical of those of the scouts. This is instrumental in the the scouts ataining their new powerws. In the manga even less is done with them. One thing is certain in both, which is that Rubeus(the sleeze!) controls them by saying he is in love with them. The sisters are fine as minor bad guys go, but not much more than that.
Hecate's OpinionI agree with Mene that the Black (or Nega) Moon sisters are rather minor as villians go. They seem to be the least developed of the R villains in the manga, and seem to me to form a sort
of preparation for the entrance of Black Lady. In the manga Carla/Avery seems to last the longest, but even she is minor character without much to her. Kind of odd in this story, ne?
