Somehow hanging around in Yuui’s kitchen means being used as an assistant. Kurogane isn’t ever quite sure how it happens, but it does happen – every time, no less – and somehow or other he’s washing his hands and chopping vegetables when all he’d meant to do originally was to drop off a file for the twins, a class schedule Yuuko had neglected to hand to them before. It’s taken for granted that he’s staying for dinner.
Fai comes in later, when Yuui’s making him stir cake-mix and has all but forced him into an apron. (It’s white, has black animal paw prints on it, and Kurogane never wants it to be spoken of again.)
Yuui smiles, Kurogane freezes, and Fai whistles, leaning against the doorpost.
“Saaa, I guess this is what they mean when they talk about puppies being domesticated?”
Fai ducks just in time to miss the wooden spoon flung at his head, laughing all the time.
(Yuui makes Kurogane clean up the cake-mix that’s spattered on the floor.)