Crystal had two modes, in the winter she ate and slept got fat and lazy but come spring she would slim down and then we'd see very little of her during the summer, she would appear at mealtimes but generally took one look at her dish then disappeared to catch herself something better
When Cider arrived she moved out, for three whole months she refused to come in except in the dead of night but as winter approached she obviously decided she needed to sort things out so back home she came, told Cider she was boss and from then on they formed a strong bond, indeed when Dad went on holiday and Cider into kennels it was Cider who got the warmest welcome home
My parents have had many cats Crystal has been the only one who would come walkies with us, once we were outside of her territory she'd start crying but walking on with us anyway
R.I.P. We'll all miss you Crystal, Dad and Cider specially.
Chrystal. Hugs for you and your dad margaret 
So sorry to hear the sad news.