We got two 6 month old brothers last October. Got them chopped and vaccinated in January and started letting them out.
Cat1 was itching to get out straight away and was quick to vanish over the fence but always came back. Cat2 is a bit more lazy and prefers to stay indoors.
We fitted a cat flap so they come and go as they please all day and night.
The last week or so I've noticed that cat1 is never in the house. They would both sleep on the spare bed, but he's not been there. He never appears for mealtimes either. However, I spot him playing in the garden now and again, occasionally with his brother!
Has he found a nice new home already and just checks in with his poor little brother now and again? Cat2 has also suddenly become a lot more clingy so I think he's missing him
'chopped' . It sounds as though he has sought out alternative slaves. Perhaps they feed him roast chicken and provide a heated cat bed? I'd be tempted to put a paper collar on him with a message asking anyone pandering to his every whim looking after him to call you.