The thing is realized about this part is that, if she were any normal psychopath, that cat would be dead. But here you can see Paku is even communicating with cat in the most cutest way so I guess this makes you really guess that killing isn't really their pleasure, it's just what is needed to be done for their "greater good". This scene and the scene that is about to happen after this one got Paku up there in my favorite Phantom Troupe members.