I know Cookie's skin is very sensitive- I'm sure any thin skinned dog/animal would feel the same way. I wouldn't dare pick her up for fear of accidentally pinching her skin. She's very touchy about that. In fact, one day while on leash one of the wiener dogs went through her legs and before I could fish him back through, the leash pinched her skin and she jumped up and bit me. I've had to teach the wiener dogs not to go through legs, which I think has improved quite a bit.
We all live and learn- and move on, hopefully with a better understanding of what we can and can't do with our pets. As far as Zero's personality change, Cookie's personality "changed", but she just got more settled in and comfortable. Her latest feat is pulling the crock part of the crock pot off the counter and breaking it.
She's also learned how to open the refrigator and unload my cupboards. She is who she is.