I've had Nancy for about 3 months and she was confident from the start. She was play fighting with my hand on the very first day I got her and her sister. I don't know if I've let it get out of hand, but when she's free roaming, she now runs up to my hand and nips it pretty hard. It never draws blood but it usually goes red and gets a little bruise. Sometimes she wrestles my hand and pins it down and nibbles my fingers then runs about excitedly and returns to do it again. Is it because I've allowed this behaviour that she's now started doing this odd attack nipping thing? How do I get her to stop? It really hurts and makes me jump.