Its been a week and ive been letting pumpernickel, a 9 wk old kitten leave the back bedroom today. She has been approached by buck, a 9 yr old cat. He sniffs her then hisses at her and goes in the living room for a couple hours. Complete supervision. No batting. She doesnt try to play with them. Boots is 13 and could care less. Just looks at her and gets back to what he was doing. Buck is kind of upset but when i pet him when she comes close to him he seems to unwind. But he was like this with boots and now: pic below. Is hissing okay? No batting yet. Buck is declawed. By previous owner. I adopted him. Im just concerned this could lead to violence but it never happened when buck came to live with boots.