remember my back story: She returned to the carnival where her love had died.She blamed herself for his death which is why she believes herself to be a cat, the literal cause of the accident that killed him. Her obsession with carnivals, marriage, and big mac are all part of her past subconsciously manifesting in her minds eye. Her relationship with the sludge is a mixture of guilt, love and disgust.
she has gone insane to the point were she doesn't know what she does is evil she just wants to run the carnival so everypony can have fun and she can stay with he lover even if that includes brainwashing,kidnapping, and murder, she has completely forgoten that sludge was what is let of him and that his undying loyalty is because his love for her. but as she slipped further into madness sludge became more of a mindless pet. she uses him for park security and also as the "water" for the tunnel of love. he is a very lethal killer do to his formless shapechanging body who is hard to injury. she really see big mac as her old lover she is beyond the point of reasoning with and probably can't even remeber his death and rebirth as sludge.