We adopted two 6 month old kittens in October 2015. They had obviously been neglected/abused poor things. Cat1 from day one had obviously been starved, constantly scavenging and howling for food. Cat2 must have been abused in some way - cowering when ever you went near, didn't like close contact with people.
Anyway, about January this year we installed a cat flap and began letting them out. All fine, except now we only see Cat2 once or twice a week. Comes in, has a nibble at the food bowls then buggers off again. I haven't seen him sleep in our house for months. He'll occasionally have a 10 minute mad dash round the house with his brother, but that's it.
I honestly think he's got another home. He looks well fed and happy, but still only likes being stroked on his terms.
So, they're annual health checks and vaccinations are due, and I'm unsure whether just to take Cat1 this year: 1) I can never guarantee when Cat2 will appear so keeping a vets appointment will be tough. Keeping him in the house and in a cat carrier will be murderous! 2) what if he has found another home and has already had his jabs? 3) Is he even our cat any more? It's so sad, but you cannot force a cat to do anything it doesn't want.
Agree with paper collar suggestion. Also someone may be putting food out for him but if he dislikes human contact it's unlikely he's simply moved into another house. Lots of people feed cats but won't take responsibility for them.
I think it would be negligent not to have him vaccinated. Until someone comes forward and says they have adopted him with full commitment to any medical treatment he's still very much your cat and your responsibility.
I'd personally lock the cat flap and encourage him to spend more time indoors now, especially with the weather turning.
He doesn't dislike humans as such, in fact I often see him running up to strangers in the street. Just isn't a very cuddly cat, dips his head when you reach down to stroke him. Certainly doesn't like our 3yo DS
The usual time we see him is just as we're leaving for work in the morning and he comes in through the front door.
I've kept him topped up with his flea drops whenever I get the opportunity.
Also doubling up on vaccines isn't dangerous. As for flea stuff, depending on what you use, as long as there are at least a few days in between that will do no harm either. If is has recently had flea treatment you will be able to smell it on his neck.