My cat started to attack my brother this morning, which was very unusual behavior. My brother takes good care of my cat, so I don't know what happened. We were scared and sent the cat outside. Before all this happened, my cat kept meowing without stopping. He is not neutered, and we also have another male cat who is his brother. They fought, so we had to separate them. But today, one of the cats started to attack. What should we do? We are scared of major injuries.