Royal Male Knight x Guard Knight

In this strange world, the people are kind and respectful. But the weirdest thing of them all, If you were born a knight, from strength, to personality, the knight's metal heads shall never come off, why? Because that IS their head. That is how they are formed at birth. Now, there are different types. Royals are very protective of such values, and protect everyone. Guard Knights protect the people living in the castle. Killer Knights... They kill the ones who kill or did something...TERRIBLE, with somebody or some people. There are many more, but that is all I can say... Reader, please do be careful. One huge wrong step here, you might as well be in jail... Or dead. Who knows? I'm just writing this. You find out what happens. I'm just a traveler.