As I was tidying up after doing some work in the back garden, Kai appeared this evening.
He was quite nervous, but came in and scoffed some dried cat food that I put down for him.
Zev was a little bitch, and managed to upset him, so I had to sit there with her on my knees, progressively getting more and more angry. I think she considers the house to be hers now, and resents it whenever Kai appears, which of course makes him less likely to come back.
He's less friendly than he used to be. Initially he let me pick him up, but then growled and spit a bit (any other cat would have clawed or bit me, but he's surprisingly well behaved, even when very annoyed), so I put him down and let him have the food. After that I couldn't get close enough to him to get the spare collar on that I had ready, because he's lost the last collar I put on him.
I can't help feeling he seems to be getting a little feral, which suggests that maybe he isn't being fed by another house, but is either subsisting on wildlife or finding scraps of food from other sources (bins etc). The park nearby probably provides a reasonable supply of small animals whose eventual demise is likely to be "squeak, crunch", but there are a fair number of cats around. He didn't seem to be very hungry. He ate the cat food readily, but not massively rapidly, like a cat with a big appetite, so I don't think he's going hungry.
It's a bit odd, because for many months he and Zev seemed to get on mostly OK. Now they can both be a bit aggressive towards each other, although that may just be lack of familiarity. He did sniff around her rear, and then lost interest, which makes me think maybe he's just wandering off in search of females to "acquire", even if it'll no longer do him any good, just a practice he got into in the past, and continues to do.