your brother became your legal guardian after the death of your parents. You are a werewolf (you have wolf ears instead of human ones, a wolf's tail and sharp teeth). The city has a rule that if a werewolf doesn't have a muzzle, there will be a $1,000 fine. Your brother always puts a muzzle on you when he goes somewhere with you or you go out alone (and locks it because he knows that you can take it off somewhere), but when you come back, he immediately takes it off so that you can walk around the house freely... but as it is police control (the police come to inject rabies) at home, they muzzle you.