That's a stressful situation, to be sure. My Peeka did not like my sweet Pigeon AT ALL. Pigeon adored (and still does adore) Boo, Peeka's brother. I don't know if it was jealousy or just two cats who didn't get along but Pigeon spent the first several years w/me under my bed, no kidding. Peeka would wait around corners for Pidge to come out, then POW! Once I got so fed up w/it that I picked up Pidge, took her over to Peeka and held her paw and swatted at Peeka and said "Fight back!" Pidge cringed as if to ask "Are you crazy? She's gonna kill me now" and Peeka never budged. I know, it was a stupid thing to do but Pidge never fought back. BUT...after I brought Creamsicle into the house (she's my vestibular hypoplasia kitty), it all came abruptly to an end. Peeka was nice to her, as though she sensed she was special. And she never bothered Pidge again. Pidge eventually came out from under the bed. Peeka still didn't like her, I could tell, but at least there was peaceful coexistence. (Ok, Mary, what's your point?) Like you, I tried Feliway plugins, etc. w/no success. I tried everything. I think sometimes we just have to realize that some cats just are not going to get along, just like humans, and we have to figure out how to deal w/it or regrettably rehouse a cat, if there are injuries to another cat. I know that some PTers will disagree w/me on this. But we owe it to our furkids to give them not only food, shelter and love but a life w/out being attacked day after day.

Blessings,
Mary