Hello! We have an orange tabby that does better with a friend. Adopted him from the shelter, and his best pal from the same shelter a week later. We have had them one year. This past week his friend (and my soul mate kitty) passed away unexpectedly. Both are (and were) 3 years old. We adopted a 6 month old kitten for a new friend for him a couple days later. He seems to have accepted him. There has been/is some hissing and growling from the older cat only. They sleep together, he grooms the kitten. However, he has begun to meow a lot, and when the kitten plays he will sit and meow at him constantly. Sometimes it is cute trills and sometimes it sounds bitchy. Should we be concerned? If left alone will they kill each other?