Cary, Ziggy and Oni have had some of the same dynamic. However it has gotten vastly better. I now feel fine about leaving them together unsupervised.
Oni has figured out that Ziggy isn't going to kill her. And she now will stop running and confront him on the ground. Yes, she still screams as if she's being killed on occasion, but it's clear she's holding her own fine.
I think that, while it's mostly them, I've done two things.
One is to continue to increase the options for escape, with a walkway between bookcases and a new cat tower. The tower has three sleeping platforms on top, and all three cats have been caught sleeping in them--4 to 6" apart. Yes, I have photos, but it was daytime and it's against a large window, so the cats are black blobs... This new space that they all want to explore and claim has really helped.
And the other is the hardest. Letting them interact. I was stepping in whenever Oni looked to be cornered. I now haven't stepped in or reacted to screaming in weeks. And I'll see Ziggy do a half-hearted walk-charge, and Oni will run, then stop and stare at him and dare him to keep coming. They're not playing, but all is good. Oni and Jax, however, play at night together when Oni thinks no one is watching!
I guess there is one more thing-- I've tried to keep their nails short.
I know Zidi is shyer than Oni, but also consider that Ziggy is almost twice her weight and size. I do give Ziggy lots of credit for figuring out that he had to take a gentler approach with Oni. He now usually will not react to her hissing, and lots of times now she doesn't even hiss when he gets too close.
Regie is gorgeous and I'm so jealous that you get to raise a kitten! My prediction is that he will totally mix things up. Give Zidi plenty of time and opportunity to interact with him. I think he'll be just fine with Kiki, once he gets the lay of the land. He could be the glue that bonds the three. < 4 weeks!
