He doesn't like the food that I have put down for him.
He has tried following me and purring. He has tried jumping up at me. He then had a tantrum, upended his dry food (which he has been eating) all over the kitchen and stormed out through the cat flap. I swear he made a rude gesture as he went.
Unfortunately it is freezing and pissing down, so he stalked back past me 20 minutes later and is now hiding upstairs.
Fussy little fucker.