Nippy is always after the invisible mice under the rugs blankets etc. Sneak likes the hands between the cushions of the couch, when she can get there before Nippy. Sneak will attack the feet under the covers if I DARE to get into bed and she has to move to make room for me. Nippy will occasionally chase the hand under the covers, when she gets tired of it and wants you to stop, she will attack your arm.