Well, folks, hubby was willing to visit the rescue shelter yesterday so I took advantage. We rescued an older, (10 yrs old) neutered male that we've named Jack (yes, our Charlie is a neutered male, too) who is very affectionate.
We did it the wrong way I guess, by keeping Jack in the carrier for a half hour or so while Charlie began to realize his world was changing, then letting him out. Charlie has been very rude, but is slowly getting adjusted. I think I only heard one hiss so far today. Actually Jack pretty much ignores Charlie. We kept them separated overnight but they've both been free to roam around the house today as they please. And it's been very quiet! Jack sprawls out where ever he feels like and sleeps quite contentedly ignoring Charlie. Charlie tries to keep an eye on Jack most of the time but has been sprawling out where ever to sleep too. I think they'll be fine in time.
We do have separate dishes and a separate litter box. Jack will have his 'meet & greet' with the vet next Thursday.
We didn't really want a kitten. We're retired and we wanted older, settled pets. We actually got Jack for free since the shelter was participating in a Million Cat Challenge that brought the adoption fee to only $20. But some donor had given money to pay the adoption fees for older cats so we didn't have to pay for him! Of course, the vet bills start next week!! Lol!