Like "your majesty" or "your highness", even though the speaker speaks directly to a monarch, why would he call him with a possessive form?
Native speaker’s answer
Rebecca
This is a great question. This is due to a particular quirk of royal etiquette. When you say “your majesty/highness,” you are not addressing the sovereign directly. You are addressing the quality of "majesty" that is considered to be unique to royalty (kings, queens, princes, princesses, etc.). Thus, "majesty" or "highness" is not their title but an attribute instead. (If you were speaking about them to another person, you would use "her/his" instead of "your." According to etiquette, if you were to use their title (king, queen, etc.), then it would be proper to use "my" to address them. Take a look at the examples below. Ex: Thank you for gracing my party with your presence, my Queen. Ex: Your Highness, the Prime Minister has arrived. Ex: His Majesty told me that he is feeling unwell.