Unrequited?

Big Ginge has been on the scene for around 5 or 6 weeks now. He's immense (hence the name) accentuated by the masses of hair. Now Isla doesn't really like other cats, but this guy has staying power. Things have settled a little from the initial hissing and spitting on sight, and they can sit and eyeball each other from a foot or so distance for a good few minutes before Isla will eventually pounce. He never runs away far, and when her back is turned he'll run towards her, but stop short as his courage leaves him. They did this for more than half an hour tonight, back and forth, Isla (tiny in comparison) constantly reminding him who is boss. It's all very odd. In two minds about him, I mean he's a gorgeous cat, and Isla is keeping him in his place, but he's also big enough that he'll try to get to the smallest chook (and is very very intent when doing so); desperately wants into the house (we're not subjecting Isla to that) and gets stroppy when you stop him; and has started knocking at the cat flap (which is chip activated, so he can't get in, but he might be big and strong enough to break it!).