[Gracie2006]

I have had lots of experience introducing new cats to an older, only cat. There will be friction for a while. I found what works best, and this may sound mean, is to let them have at it while you are home and can supervise. When you must leave them alone, keep them separated. When I introduced a female kitten to a 5 year old male, my male hid under the bed, hissed and spit, and would not come out or eat for 3 days. Within 6 months, he was very protective of the younger one. They became best friends. There will be a time where you may observe the hissing, spitting, etc. Sometimes I think they do that just so you won't figure out that they have become friends. The older cat just needs time to a accept the younger cat into the group. Good luck.