Warning: NSFW
Food aggression is a commonality in the animal kingdom with the closest example being dogs. This behaviour of being overprotective over food was passed down in evolution making it fairly common.
But Ji Yao was neither a dog nor overprotective over all his meals. He was just overprotective of the food Rui Fei made for him, especially the sweet stuff. There was no way he was going to let him walk out of this room with that plate thus he threatened to kick Rui Fei out if he so much as takes a step towards the cabin door.
With an expression that seemed to say, 'You can walk out but the plate stays,' plastered on his face Ji Yao pulled the plate back with a subtle scraping sound.