let them learn each other's scent until they stop hissing and swatting at each other. One trick that sometimes works is to rub both cats with vanilla extract so they smell the same.

We used to rub ours with diluted cheap vodka (half & half with warm water) to keep them from fighting. It doubled as “cleaning solution” for upholstery with pet stains. 🤣

Use the vodka UNDILUTED in their water bowl…10 minutes later …

”I luvs ya’ man”
“Luv you too man”
“We shud hang out more man”
“I know I know…we shud hunt mice tomorrow”
“Or crickets…hunting crickets is fun too”
“Let’s get anuder drink man”
“Yeah, let’s get anuder drink then claw that human…whadya think?”
“Yeah, drink…then human, then claw the couch”
“Oh man, yur my kinda guy…yeah, another drink then.”

I neglected to mention that my brother and I used the leftover cheap vodka to make “Dirty Mary,” a drink we invented using the “cleaning fluid” vodka (undiluted, of course), V-8, and a carrot stick.

Kitties didn’t seem all that interested, but perhaps our invitation wasn’t properly engraved. We normally don’t put surprises in their bowl. As you pointed out, it could’ve been a lot more fun!

I kept the new kitten (Riley) in the bedroom with the door closed and moved Freddie’s food bowls to right outside the bedroom door. He got to associate something good with the scent of the kitten. Pretty soon Riley would put his paws under the door and they would play (I think) batting paws. After a couple days I had a formal introduction and they ended up as good pals.