We recently adopted Simon, a one year old neutered male, as a companion for our three year old spayed female. Both are strictly housecats. The previous owner said that Simon was an outgoing and loveable cat that had a tendency to be shy around strangers. He was very close to his sister who was given away previously the day before. I'm sure that he is grieving for her as well. It has been three days and Simon is still in hiding. I don't know if he has eaten or not but food and water are available. We have tried to make frequent attempts to pet and talk to him but he will not emerge from his hiding place willingly. Our female cat does not seem to mind his presence. I want to make his transition into our home a happy and healthy one. If someone could recommend a few helpful tips to help Simon overcome this new era it would be most appreciated and also a criteria for how long I should expect this behavior to linger.