Cats are supposed to hunt rats, not the reverse. Cats are not supposed to be chased, intimidated or harassed by rats. The nature of the cat is to hunt and dominate rats, but apparently it can be lulled out of its instinct by being spoiled.
So too the Christian is not supposed to be pushed around by the devil. It is their nature, their spiritual DNA, to hunt and kill devils, to free sinners from demons’ oppression. But we can be lulled out of our very nature. When we look for self-pleasing and self-blessing, we forget who we are. Then this rat becomes a picture of the devil chasing us around.